View Filing Data

Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2014	May 05, 2014
Document and Entity Information
Entity Registrant Name	PTC THERAPEUTICS, INC.
Entity Central Index Key	0001070081
Document Type	10-Q
Document Period End Date	Mar. 31, 2014
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		30,074,453
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	Q1

Balance sheets - USD ($) $ in Thousands	Mar. 31, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 115,855	$ 15,414
Marketable securities	130,730	127,053
Prepaid expenses and other current assets	1,957	1,599
Grant and collaboration receivables, net	838	958
Total current assets	249,380	145,024
Fixed assets, net	6,328	6,730
Deposits and other assets	132	149
Total assets	255,840	151,903
Current liabilities:
Accounts payable and accrued expenses	8,735	12,207
Current portion of long-term debt	12	49
Deferred revenue	492	878
Total current liabilities	9,239	13,134
Other long-term liabilities	2,259	2,227
Total liabilities	11,498	15,361
Stockholders' equity:
Preferred stock, $0.001 par value. Undesignated 5,000,000 shares; issued and outstanding 0 shares at March 31, 2014 and December 31, 2013
Common stock, $0.001 par value. Authorized 125,000,000 shares; issued and outstanding 29,325,997 shares at March 31, 2014. Authorized 125,000,000 shares; issued and outstanding 23,803,282 shares at December 31, 2013	30	24
Additional paid-in capital	587,128	465,246
Accumulated other comprehensive loss	80	70
Accumulated deficit	(342,896)	(328,798)
Total stockholders' equity	244,342	136,542
Total liabilities and stockholders' equity	$ 255,840	$ 151,903

Balance sheets (Parenthetical) - $ / shares	Mar. 31, 2014	Dec. 31, 2013
Balance sheets
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, undesignated shares	5,000,000	5,000,000
Preferred stock, issued shares	0	0
Preferred stock, outstanding shares	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, authorized shares	125,000,000	125,000,000
Common stock, issued shares	29,325,997	23,803,282
Common stock, outstanding shares	29,325,997	23,803,282

Statements of operations - USD ($) $ in Thousands	3 Months Ended
Statements of operations - USD ($) $ in Thousands	Mar. 31, 2014	Mar. 31, 2013
Revenues:
Collaboration revenue	$ 9,147	$ 6,072
Grant revenue	70	1,070
Total revenues	9,217	7,142
Operating expenses:
Research and development	15,889	11,257
General and administrative	7,540	4,461
Total operating expenses	23,429	15,718
Loss from operations	(14,212)	(8,576)
Interest income (expense), net	171	(6,162)
Other (expense) income, net	(57)	54
Net loss	(14,098)	(14,684)
Deemed dividend		(18,249)
Gain on exchange of convertible preferred stock in connection with recapitalization		3,391
Net loss attributable to common stockholders	$ (14,098)	$ (29,542)
Weighted-average shares outstanding:
Basic and diluted (in shares)	24,492,487	4,526
Net loss per share applicable to common stockholders-basic and diluted (in dollars per share)	$ (0.58)	$ (6,527.30)

Statements of comprehensive loss - USD ($) $ in Thousands	3 Months Ended
Statements of comprehensive loss - USD ($) $ in Thousands	Mar. 31, 2014	Mar. 31, 2013
Statements of comprehensive loss
Net loss	$ (14,098)	$ (14,684)
Other comprehensive loss:
Unrealized gain on marketable securities	10
Comprehensive loss	$ (14,088)	$ (14,684)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Net Income
-URI http://asc.fasb.org/extlink&oid=6518256

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.19)
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.18)
-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.22)
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Other Comprehensive Income
-URI http://asc.fasb.org/extlink&oid=6519514

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=28358780&loc=d3e565-108580

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 19
-Article 5

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph 20
-Article 9

+ Details

Statements of cash flows - USD ($) $ in Thousands	3 Months Ended
Statements of cash flows - USD ($) $ in Thousands	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities
Net loss	$ (14,098)	$ (14,684)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	588	625
Change in valuation of warrant liability	55	(54)
Non-cash interest expense		6,023
Amortization of premiums on investments	414
Share-based compensation expense	3,705	621
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(358)	(25)
Grant and collaboration receivables	120	68
Deposits and other assets	17	39
Accounts payable and accrued expenses	(3,472)	4,446
Other long-term liabilities	(23)	1
Deferred revenue	(386)	(4,907)
Net cash used in operating activities	(13,438)	(7,847)
Cash flows from investing activities
Purchases of fixed assets	(186)	(21)
Purchases of marketable securities	(25,354)
Maturities of marketable securities	21,273
Net cash used in investing activities	(4,267)	(21)
Cash flows from financing activities
Payments on long-term debt	(37)	(1,069)
Net proceeds from sale of Series Four convertible preferred stock		56,458
Net proceeds from secondary offering	118,183
Net cash provided by financing activities	118,146	55,389
Net increase in cash and cash equivalents	100,441	47,521
Cash and cash equivalents, beginning of period	15,414	2,726
Cash and cash equivalents, end of period	115,855	50,247
Supplemental disclosure of cash information
Cash paid for interest	1	162
Supplemental disclosures of non-cash information related to investing and financing activities
Change in unrealized gain on marketable securities	$ 10
Change in carry value of preferred securities resulting from recapitalization		$ 3,391

Fair value of financial instruments and marketable securities

3 Months Ended

Mar. 31, 2014

Fair value of financial instruments and marketable securities

Fair value of financial instruments and marketable securities

3. Fair value of financial instruments and marketable securities

The Company follows the fair value measurement rules, which provides guidance on the use of fair value in accounting and disclosure for assets and liabilities when such accounting and disclosure is called for by other accounting literature. These rules establish a fair value hierarchy for inputs to be used to measure fair value of financial assets and liabilities. This hierarchy prioritizes the inputs to valuation techniques used to measure fair value into three levels: Level 1 (highest priority), Level 2, and Level 3 (lowest priority).

· Level 1—Unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the balance sheet date.

· Level 2—Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly. Level 2 inputs include quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability (i.e., interest rates, yield curves, etc.), and inputs that are derived principally from or corroborated by observable market data by correlation or other means (market corroborated inputs).

· Level 3—Inputs are unobservable and reflect the Company’s assumptions as to what market participants would use in pricing the asset or liability. The Company develops these inputs based on the best information available.

Cash equivalents are reflected in the accompanying financial statements at fair value. The carrying amount of grant and collaboration receivables, accounts payable and accrued expenses, and debt approximates fair value due to the short-term nature of those instruments.

Fair value of certain marketable securities is based upon market prices using quoted prices in active markets for identical assets quoted on the last day of the period. In establishing the estimated fair value of the remaining investments, the Company used the fair value as determined by its investment advisors using observable inputs other than quoted prices.

The Company reviews its investments on a periodic basis for other-than-temporary impairments. This review is subjective, as it requires management to evaluate whether an event or change in circumstances has occurred in that period that may have a significant adverse effect on the fair value of the investment.

The following represents the fair value using the hierarchy described above for the Company’s financial assets and liabilities that are required to be measured at fair value on a recurring basis as of March 31, 2014 and December 31, 2013:

	March 31, 2014
	Total		Quoted prices in active markets for identical assets (level 1)		Significant other observable inputs (level 2)		Significant unobservable inputs (level 3)
Marketable securities	$	130,730	$	—	$	130,730	$	—
Warrant liability	113		—		—		113

	December 31, 2013
	Total		Quoted prices in active markets for identical assets (level 1)		Significant other observable inputs (level 2)		Significant unobservable inputs (level 3)
Marketable securities	$	127,053	$	—	$	127,053	$	—
Warrant Liability	58		—		—		58

The following is a summary of marketable securities accounted for as available-for-sale securities at March 31, 2014 and December 31, 2013:

	March 31, 2014
	Amortized		Gross Unrealized					Fair
	Cost		Gains		Losses			Value
Commercial paper	$	3,998	$	2	$	—		$	4,000
U.S. corporate debt securities	126,651		115		(36		)	126,730
	$	130,649	$	117	$	(36	)	$	130,730

	December 31, 2013
	Amortized		Gross Unrealized					Fair
	Cost		Gains		Losses			Value
Commercial paper	$	14,993	$	5	$	—		$	14,998
U.S. corporate debt securities	111,989		97		(31		)	112,055
	$	126,982	$	102	$	(31	)	$	127,053

At March 31, 2014 and December 31, 2013, the Company held securities with an unrealized loss position that were not considered to be other-than-temporarily impaired as the Company has the ability to hold such investments until recovery of their fair value.

Marketable securities on the balance sheet at March 31, 2014 and December 31, 2013 mature as follows:

	March 31, 2014
	Less Than 12 Months		More Than 12 Months
Commercial paper	$	4,000	$	—
U.S. corporate debt securities	74,509		52,221
Total Marketable securities	$	78,509	$	52,221

	December 31, 2013
	Less Than 12 Months		More Than 12 Months
Commercial paper	$	14,998	$	—
U.S. corporate debt securities	54,159		57,896
Total Marketable securities	$	69,157	$	57,896

Level 3 valuation

The warrant liability is classified in Other long-term liabilities on the Company’s balance sheet. The warrant liability is marked-to-market each reporting period with the change in fair value recorded as a gain or loss within Other income (expense), net on the Company’s statement of operations until the warrants are exercised, expire or other facts and circumstances lead the warrant liability to be reclassified as an equity instrument. The fair value of the warrant liability is determined at each reporting period by utilizing the Black-Scholes option pricing model.

The table presented below is a summary of changes in the fair value of the Company’s Level 3 valuation for warrant liability for the period ended March 31, 2014:

	Level 3 assets
Beginning balance as of December 31, 2013	$	58
Change in fair value of warrant liability	55
Ending balance as of March 31, 2014	$	113

Fair value of the warrant liability is estimated using an option-pricing model, which includes variables such as the expected volatility based on guideline public companies, the stock fair value, and the estimated time to a liquidity event. The significant assumptions used in preparing the option pricing model for valuing the Company’s warrants as of March 31, 2014 include (i) volatility (58-90%), (ii) risk free interest rate (0.03%—1.73%), (iii) strike price ($128.00—$2,520.00), (iv) fair value of common stock ($26.14), and (v) expected life (0.06—5.48 years). The significant assumptions used in preparing the option pricing model for valuing the Company’s warrants as of December 31, 2013 include (i) volatility (61-89%), (ii) risk free interest rate (0.07%—2.10%), (iii) strike price ($128.00—$2,520.00), (iv) fair value of common stock ($16.97), and (v) expected life (0.30—5.70 years). See Note 6 for a description of the warrants issued in connection with the convertible notes.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Other comprehensive income (loss) and accumulated other comprehensive items

3 Months Ended

Mar. 31, 2014

Other comprehensive income (loss) and accumulated other comprehensive items

Other comprehensive income (loss) and accumulated other comprehensive items

4. Other comprehensive income (loss) and accumulated other comprehensive items

Other comprehensive income (loss) includes changes in equity that are excluded from net income (loss), such as unrealized gains and losses on marketable securities.

The following table summarizes other comprehensive loss and the changes in accumulated other comprehensive items for the three months ended March 31, 2014:

	Unrealized Gains On Marketable Securities		Total Accumulated Other Comprehensive Items

Balance at December 31, 2013	$	70	$	70
Other comprehensive income before reclassifications	10		10
Amounts reclassified from other comprehensive items	—		—
Other comprehensive income	10		10
Balance at March 31, 2014	$	80	$	80

- Definition

The entire disclosure for comprehensive income, which includes, but is not limited to, 1) the amount of income tax expense or benefit allocated to each component of other comprehensive income, including reclassification adjustments, 2) the reclassification adjustments for each classification of other comprehensive income and 3) the ending accumulated balances for each component of comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=28358780&loc=d3e689-108580

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=28358780&loc=SL7669619-108580

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=28358780&loc=d3e640-108580

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=28358780&loc=d3e716-108580

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 16
-URI http://asc.fasb.org/extlink&oid=28358780&loc=d3e709-108580

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=28358780&loc=d3e637-108580

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14
-URI http://asc.fasb.org/extlink&oid=28358780&loc=d3e681-108580

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Reclassification Adjustments
-URI http://asc.fasb.org/extlink&oid=6522872

+ Details

Capital structure

3 Months Ended

Mar. 31, 2014

Capital structure

Capital structure

6. Capital structure

2013 Recapitalization

During January and February of 2013, the Company entered into a “bridge” financing arrangement with certain existing investors providing for the issuance by the Company of an aggregate of $6 million of convertible promissory notes and warrants to purchase 2,527,675 shares of Series One convertible preferred stock (Series One) and Series Two convertible preferred stock (Series Two). The warrants had a per share exercise price of $0.01, and as such, they are referred to as “penny warrants”. This bridge financing was closed in anticipation of the March 2013 Series Four financing event, which the Company refers to as the “2013 recapitalization”.

The Company allocated the proceeds of the convertible promissory notes between debt and warrant liability. Since the value of the warrants exceeded the proceeds from the convertible notes issued to existing investors, the value of the warrant in excess of the proceeds is considered a deemed dividend and reflected as an equity transaction in the financial statements. The Company recorded $6 million to interest expense related to the debt discount associated with the convertible debt during the quarter ended March 31, 2013.

On March 7, 2013, the Company closed a private placement of a new series of convertible preferred stock that resulted in the 2013 recapitalization. In this private placement, the Company issued and sold an aggregate of 4,497,035 shares of its Series Four senior preferred stock (Series Four) for an aggregate purchase price of approximately $54 million. Including the $6 million raised with the bridge financing, total gross proceeds raised during the quarter ended March 31, 2013 was approximately $60 million. In addition, the Company issued an aggregate of 502,919 shares of Series Four upon the share settlement of the convertible promissory notes described above that were issued in January and February 2013.

In connection with this private placement, the Company effected a one-for-120 reverse stock split of its common stock and an exchange of outstanding shares of Series One, Series Two and Series Three convertible preferred stock (Series Three) into an aggregate of 6,700,487 shares of a new series of Series Five junior preferred stock (Series Five). In addition, the Company issued an aggregate of 2,527,675 shares of Series One and Series Two upon the exercise of the warrants issued in connection with the bridge loan that were immediately exchanged for 2,095,515 shares of Series Five during the 2013 recapitalization.

The Company accounted for the 2013 recapitalization as an extinguishment of its Series One, Series Two and Series Three convertible preferred stock and recorded the Series Five shares at their fair value as of the recapitalization date. In accordance with authoritative accounting guidance, the Company recorded a gain attributable to the common stockholders on the extinguishment of the Series One, Series Two and Series Three. The gain of approximately $3.4 million represents the excess of the Series One, Series Two and Series Three over the fair value of the shares Series Five issued in connection with the recapitalization.

Initial Public Offering

In June 2013, the Company closed the initial public offering of its common stock pursuant to a registration statement on Form S-1, as amended. The Company issued and sold an aggregate of 9,627,800 shares of common stock under the registration statement at a public offering price of $15.00 per share, including 1,255,800 shares pursuant to the exercise by the underwriters of an over-allotment option. The Company received net proceeds from the initial public offering of approximately $131.6 million, after deducting underwriting discounts and commissions and other offering expenses payable by the Company.

Upon closing the initial public offering, all outstanding shares of the Series Four and Series Five were converted into 14,170,956 shares of common stock.

Follow-On Offering

In February 2014, the Company closed a follow-on public offering of its common stock pursuant to a registration statement on Form S-1, as amended. The Company issued and sold an aggregate of 5,163,265 shares of common stock under the registration statement at a public offering price of $24.50 per share, including 673,469 shares pursuant to the exercise by the underwriters of an over-allotment option. The Company received net proceeds from the initial public offering of approximately $118.2 million, after deducting underwriting discounts and commissions and other offering expenses payable by the Company.

Warrants

All of the Company’s outstanding warrants were classified as liabilities as of March 31, 2014 and December 31, 2013 because they contained non-standard antidilution provisions.

The following is a summary of the Company’s outstanding warrants as of March 31, 2014 and December 31, 2013:

	Warrant shares	Exercise price		Expiration
Common stock	1,428	$	128.00	2014
Common stock	6,250	$	128.00	2017
Common stock	7,030	$	128.00	2019 and 2020
Common stock	452	$	2,520.00	2014

In connection with the 2013 recapitalization, all of the Series Two outstanding warrants became warrants to purchase Series Five. In connection with the Company’s initial public offering all of the Series Five outstanding warrants became warrants to purchase common stock.

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(d),(e))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21484-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB TOPIC 4.E)
-URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74512-122707

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21488-112644

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.29-31)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SAB TOPIC 4.C)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187143-122770

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21506-112644

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 30
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6405834&loc=d3e23285-112656

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Preferred Stock
-URI http://asc.fasb.org/extlink&oid=6521494

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21564-112644

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Paragraph d
-Article 4

Reference 15: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 29, 30, 31
-Article 5

Reference 16: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 4
-Section E

Reference 17: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Article 4

Reference 18: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 4
-Section C

Reference 19: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Article 3

+ Details

Net loss per share

3 Months Ended

Mar. 31, 2014

Net loss per share

Net loss per share

7. Net loss per share

Basic earnings per share is computed by dividing net loss available to common stockholders by the weighted-average number of common shares outstanding. Diluted earnings per share is computed by dividing net income (loss) available to common stockholders by the weighted-average number of common shares plus the effect of dilutive potential common shares outstanding during the period.

The following tables set forth the computation of basic and diluted net loss per share for common stockholders:

	Three months ended March 31,
	2014			2013
Numerator
Net loss	$	(14,098	)	$	(14,684	)
Deemed dividend	—			(18,249		)
Gain on exchange of convertible preferred stock in connection with recapitalization	—			3,391
Net loss attributable to common stockholders	$	(14,098	)	$	(29,542	)
Denominator
Denominator for basic and diluted net loss per share	24,492,487			4,526
Net loss per share:
Basic and diluted	$	(0.58	)*	$	(6,527.30	)*

* In the three months ended March 31, 2014 and 2013, the Company experienced a net loss and therefore did not report any dilutive share impact.

The following table shows historical dilutive common share equivalents outstanding, which are not included in the above historical calculation, as the effect of their inclusion is anti-dilutive during each period.

	As of March 31,
	2014	2013
Stock Options	3,133,830	46,642
Unvested restricted stock	748,456	735,324
Total	3,882,286	781,966

Stock award plan

3 Months Ended

Mar. 31, 2014

Stock award plan

Stock award plan

8. Stock award plan

On March 5, 2013, the Company’s Board of Directors approved the 2013 Stock Incentive Plan, which provides for the granting of stock option awards, stock appreciation rights, restricted stock, restricted stock units and other stock-based awards in the aggregate of 739,937 shares of common stock. On March 5, 2013, the Board approved a grant of 735,324 shares of restricted stock and 4,613 stock options. There are no additional shares available for issuance under this plan.

In May 2013, the Company’s Board of Directors and stockholders increased by 2,500,000 the number of shares authorized under the 2009 Stock Incentive Plan, which provides for the granting of stock option awards, restricted stock awards, and other stock-based and cash-based awards.

In May 2013, the Company’s Board of Directors and stockholders approved the 2013 Long Term Incentive Plan, which became effective upon the closing of the Company’s IPO. The 2013 Long Term Incentive Plan provides for the grant of incentive stock options, nonstatutory stock options, restricted stock awards and other stock-based awards. The number of shares of common stock reserved for issuance under the 2013 Long Term Incentive Plan is the sum of (1) 122,296 shares of common stock available for issuance under the Company’s 2009 Equity and Long Term Incentive Plan and 2013 Stock Incentive Plan, (2) the number of shares (up to 3,040,444 shares) equal to the sum of the number of shares of common stock subject to outstanding awards under the Company’s 1998 Employee, Director and Consultant Stock Option Plan and 2013 Stock Incentive Plan that expire, terminate or are otherwise surrendered, cancelled, forfeited or repurchased by the Company at their original issuance price pursuant to a contractual repurchase right plus (3) an annual increase, to be added on the first day of each fiscal year until the expiration of the 2013 Long Term Incentive Plan, equal to the lowest of 2,500,000 shares of common stock, 4% of the number of shares of common stock outstanding on the first day of the fiscal year and an amount determined by the Company’s Board of Directors.

A summary of stock option activity is as follows:

	Number of options		Exercise price		Weighted- average exercise price		Weighted- average remaining contractual term	Aggregate intrinsic value
								(in thousands)
Outstanding at December 31, 2013	2,095,592		$	10.59—1,149.60	$	20.24
Granted	1,121,196		$	26.07—33.97	$	27.95
Exercised	—		$		$
Forfeited	(82,964	)	$	10.85—490.80	$	11.43
Outstanding at March 31, 2014	3,133,824		$	10.59—1,149.60	$	23.23	9.33 years	$	29,217
Vested or expected to vest at March 31, 2014	2,880,322				$	21.67	9.37 years	$	27,210
Exercisable at March 31, 2014	183,214				$	107.87	7.95 years	$	2,224

The fair value of grants made in the period ended March 31, 2014 was contemporaneously estimated on the date of grant using the following assumptions:

		Three months ended March 31, 2014
Risk-free interest rate		0.11%—1.91%
Expected volatility		89%—90%
Expected term		5.50—6.25 years

The Company assumed no expected dividends for all grants. The weighted average grant date fair value of options granted during the three month period ended March 31, 2014 was $20.88 per share.

The Company uses the “simplified method” to determine the expected term of options. Under this method, the expected term represents the average of the vesting period and the contractual term. The expected volatility of share options was estimated based on a historical volatility analysis of peers that were similar to the Company with respect to industry, stage of life cycle, size, and financial leverage. The risk-free rate of the option is based on U.S. Government Securities Treasury Constant Maturities yields at the date of grant for a term similar to the expected term of the option.

Restricted Stock Awards—Restricted stock awards are granted subject to certain restrictions, including in some cases service conditions (restricted stock). The grant-date fair value of restricted stock awards, which has been determined based upon the market value of the Company’s shares on the grant date, is expensed over the vesting period.

The following table summarizes information on the Company’s restricted stock:

	Restricted Stock
	Number of Shares		Weighted Average Grant Date Fair Value
January 1, 2014	1,110,226		$	10.68
Granted	—
Vested	(359,450	)	$	10.59
Forfeited	(2,320	)	$	10.59
Unvested at March 31, 2014	748,456		$	10.73

The Company recorded share-based compensation expense in the statement of operations as follows:

	Three Months Ended March 31,
	2014		2013

Research and development	$	1,944	$	257
General and administrative	1,761		364
Total	$	3,705	$	621

As of March 31, 2014 there was approximately $40.1 million of total unrecognized compensation cost related to unvested share-based compensation arrangements granted under the 1998, 2009 and 2013 Plans. This cost is expected to be recognized as share-based compensation expense over the weighted average remaining service period of approximately 2.88 years.

Fair value of financial instruments and marketable securities (Tables)

3 Months Ended

Mar. 31, 2014

Fair value of financial instruments and marketable securities

Schedule of financial assets and liabilities that are required to be measured at fair value on a recurring basis

	March 31, 2014
	Total		Quoted prices in active markets for identical assets (level 1)		Significant other observable inputs (level 2)		Significant unobservable inputs (level 3)
Marketable securities	$	130,730	$	—	$	130,730	$	—
Warrant liability	113		—		—		113

	December 31, 2013
	Total		Quoted prices in active markets for identical assets (level 1)		Significant other observable inputs (level 2)		Significant unobservable inputs (level 3)
Marketable securities	$	127,053	$	—	$	127,053	$	—
Warrant Liability	58		—		—		58

Summary of marketable securities accounted for as available-for-sale securities

	March 31, 2014
	Amortized		Gross Unrealized					Fair
	Cost		Gains		Losses			Value
Commercial paper	$	3,998	$	2	$	—		$	4,000
U.S. corporate debt securities	126,651		115		(36		)	126,730
	$	130,649	$	117	$	(36	)	$	130,730

	December 31, 2013
	Amortized		Gross Unrealized					Fair
	Cost		Gains		Losses			Value
Commercial paper	$	14,993	$	5	$	—		$	14,998
U.S. corporate debt securities	111,989		97		(31		)	112,055
	$	126,982	$	102	$	(31	)	$	127,053

Schedule of marketable securities on the balance sheet

	March 31, 2014
	Less Than 12 Months		More Than 12 Months
Commercial paper	$	4,000	$	—
U.S. corporate debt securities	74,509		52,221
Total Marketable securities	$	78,509	$	52,221

	December 31, 2013
	Less Than 12 Months		More Than 12 Months
Commercial paper	$	14,998	$	—
U.S. corporate debt securities	54,159		57,896
Total Marketable securities	$	69,157	$	57,896

Summary of changes in the fair value of the Company's Level 3 valuation for warrant liability

	Level 3 assets
Beginning balance as of December 31, 2013	$	58
Change in fair value of warrant liability	55
Ending balance as of March 31, 2014	$	113

Net loss per share (Tables)

3 Months Ended

Mar. 31, 2014

Net loss per share

Schedule of computation of basic and diluted net loss per share for common stockholders

	Three months ended March 31,
	2014			2013
Numerator
Net loss	$	(14,098	)	$	(14,684	)
Deemed dividend	—			(18,249		)
Gain on exchange of convertible preferred stock in connection with recapitalization	—			3,391
Net loss attributable to common stockholders	$	(14,098	)	$	(29,542	)
Denominator
Denominator for basic and diluted net loss per share	24,492,487			4,526
Net loss per share:
Basic and diluted	$	(0.58	)*	$	(6,527.30	)*

* In the three months ended March 31, 2014 and 2013, the Company experienced a net loss and therefore did not report any dilutive share impact.

Schedule of historical dilutive common share equivalents outstanding

	As of March 31,
	2014	2013
Stock Options	3,133,830	46,642
Unvested restricted stock	748,456	735,324
Total	3,882,286	781,966

Stock award plan (Tables)

3 Months Ended

Mar. 31, 2014

Stock award plan

Summary of stock option activity

	Number of options		Exercise price		Weighted- average exercise price		Weighted- average remaining contractual term	Aggregate intrinsic value
								(in thousands)
Outstanding at December 31, 2013	2,095,592		$	10.59—1,149.60	$	20.24
Granted	1,121,196		$	26.07—33.97	$	27.95
Exercised	—		$		$
Forfeited	(82,964	)	$	10.85—490.80	$	11.43
Outstanding at March 31, 2014	3,133,824		$	10.59—1,149.60	$	23.23	9.33 years	$	29,217
Vested or expected to vest at March 31, 2014	2,880,322				$	21.67	9.37 years	$	27,210
Exercisable at March 31, 2014	183,214				$	107.87	7.95 years	$	2,224

Schedule of assumptions used to estimate fair value of grants made on the date of grant

		Three months ended March 31, 2014
Risk-free interest rate		0.11%—1.91%
Expected volatility		89%—90%
Expected term		5.50—6.25 years

Summary of information on the Company's restricted stock

	Restricted Stock
	Number of Shares		Weighted Average Grant Date Fair Value
January 1, 2014	1,110,226		$	10.68
Granted	—
Vested	(359,450	)	$	10.59
Forfeited	(2,320	)	$	10.59
Unvested at March 31, 2014	748,456		$	10.73

Schedule of share-based compensation expense recorded in the statement of operations

Table 4

	Three Months Ended March 31,
	2014		2013

Research and development	$	1,944	$	257
General and administrative	1,761		364
Total	$	3,705	$	621

Fair value of financial instruments and marketable securities (Details 4) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Jun. 30, 2013
Common stock
Assumption used to estimate the fair value of warrant liability by utilizing the Black-Scholes option-pricing model
Fair value of shares (in dollars per share)			$ 15.00
Warrant
Changes in the fair value of warrant liability
Beginning balance	$ 58
Change in fair value of warrant liability	55
Ending balance	$ 113	$ 58
Warrant \| Minimum
Assumption used to estimate the fair value of warrant liability by utilizing the Black-Scholes option-pricing model
Volatility (as a percent)	58.00%	61.00%
Risk-free interest rate (as a percent)	0.03%	0.07%
Strike price (in dollars per share)	$ 128.00	$ 128.00
Expected life	22 days	3 months 18 days
Warrant \| Maximum
Assumption used to estimate the fair value of warrant liability by utilizing the Black-Scholes option-pricing model
Volatility (as a percent)	90.00%	89.00%
Risk-free interest rate (as a percent)	1.73%	2.10%
Strike price (in dollars per share)	$ 2,520.00	$ 2,520.00
Expected life	5 years 5 months 23 days	5 years 8 months 12 days
Warrant \| Common stock
Assumption used to estimate the fair value of warrant liability by utilizing the Black-Scholes option-pricing model
Fair value of shares (in dollars per share)	$ 26.14	$ 16.97

Accounts payable and accrued expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2014	Dec. 31, 2013
Accounts payable and accrued expenses
Employee compensation, benefits, and related accruals	$ 2,145	$ 5,103
Consulting and contracted research	3,516	4,006
Professional fees	1,960	1,294
Accounts payable	387	1,124
Other	727	680
Accounts payable and accrued expenses	$ 8,735	$ 12,207

Capital structure (Details) $ / shares in Units, $ in Thousands			1 Months Ended	3 Months Ended
	Feb. 12, 2014 USD ($) $ / shares shares	Mar. 07, 2013 USD ($) shares	Jun. 30, 2013 USD ($) $ / shares shares	Mar. 31, 2014 USD ($)	Mar. 31, 2013 USD ($)	Feb. 28, 2013 USD ($) $ / shares shares
Capital structure
Gross proceeds raised \| $					$ 60,000
Gain on extinguishment of shares of Series One, Two and Three stock \| $					3,391
Period of option	30 days
Net proceeds from secondary offering \| $				$ 118,183
Series One and Series Two \| Warrants
Capital structure
Warrants issued to purchase shares						2,527,675
Exercise price (in dollars per share) \| $ / shares						0.01
Shares issued and sold		2,527,675
Series Four
Capital structure
Shares issued and sold		4,497,035
Aggregate gross proceeds \| $		$ 54,000
Series Five
Capital structure
Number of shares issued upon conversion		6,700,487
Series Five \| Warrants
Capital structure
Number of shares issued upon conversion		2,095,515
Common stock
Capital structure
Shares issued and sold	5,163,265		9,627,800
Reverse stock split ratio		0.0083
Share price (in dollars per share) \| $ / shares			$ 15.00
Public offering price (in dollars per share) \| $ / shares	$ 24.50
Common stock shares issuable pursuant to the exercise by the underwriters of an over-allotment option			1,255,800
Net proceeds from initial public offering \| $			$ 131,600
Net proceeds from secondary offering \| $	$ 118,200
Common stock \| Maximum
Capital structure
Common stock shares issuable pursuant to the exercise by the underwriters of an over-allotment option	673,469
Series Four and Series Five Convertible Preferred Stock
Capital structure
Number of shares issued upon conversion			14,170,956
Convertible promissory notes
Capital structure
Principal amount of convertible promissory notes issued \| $						$ 6,000
Debt discount recorded to interest expense \| $					6,000
Amount raised in bridge financing \| $					$ 6,000
Convertible promissory notes \| Series Four
Capital structure
Shares issued upon conversion of convertible promissory notes		502,919

Net loss per share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Numerator
Net loss	$ (14,098)	$ (14,684)
Deemed dividend		(18,249)
Gain on exchange of convertible preferred stock in connection with recapitalization		3,391
Net loss attributable to common stockholders	$ (14,098)	$ (29,542)
Denominator
Denominator for basic and diluted net loss per share (in shares)	24,492,487	4,526
Net loss per share:
Basic and diluted (in dollars per share)	$ (0.58)	$ (6,527.30)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

+ Details

Stock award plan (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	3 Months Ended
	Mar. 05, 2013	May 31, 2013	Mar. 31, 2014
Stock options
Number of options
Outstanding at the beginning of the period (in shares)			2,095,592
Granted (in shares)			1,121,196
Forfeited (in shares)			(82,964)
Outstanding at the end of the period (in shares)			3,133,824
Vested or expected to vest at the end of the period (in shares)			2,880,322
Exercisable at the end of the period (in shares)			183,214
Weighted-average exercise price
Outstanding at the beginning of the period (in dollars per share)			$ 20.24
Granted (in dollars per share)			27.95
Forfeited (in dollars per share)			11.43
Outstanding at the end of the period (in dollars per share)			23.23
Vested or expected to vest at the end of the period (in dollars per share)			21.67
Exercisable at the end of the period (in dollars per share)			$ 107.87
Weighted-average remaining contractual term
Outstanding at the end of the period			9 years 3 months 29 days
Vested or expected to vest at the end of the period			9 years 4 months 13 days
Exercisable at the end of the period			7 years 11 months 12 days
Aggregate intrinsic value
Outstanding at the end of the period (in dollars)			$ 29,217
Vested or expected to vest at the end of the period (in dollars)			27,210
Exercisable at the end of the period (in dollars)			$ 2,224
Valuation assumptions
Weighted average grant date fair value (in dollars per share)			$ 20.88
Stock options \| Minimum
Exercise price
Outstanding at the beginning of the period (in dollars per share)			10.59
Granted (in dollars per share)			26.07
Forfeited (in dollars per share)			10.85
Outstanding at the end of the period (in dollars per share)			$ 10.59
Valuation assumptions
Risk-free interest rate (as a percent)			0.11%
Expected volatility (as a percent)			89.00%
Expected term			5 years 6 months
Stock options \| Maximum
Exercise price
Outstanding at the beginning of the period (in dollars per share)			$ 1,149.60
Granted (in dollars per share)			33.97
Forfeited (in dollars per share)			490.80
Outstanding at the end of the period (in dollars per share)			$ 1,149.60
Valuation assumptions
Risk-free interest rate (as a percent)			1.91%
Expected volatility (as a percent)			90.00%
Expected term			6 years 3 months
2013 Stock Incentive Plan
Stock option plan
Number of shares available for issuance	0
2013 Stock Incentive Plan \| Stock options
Stock option plan
Number of shares of restricted stock granted	4,613
2013 Stock Incentive Plan \| Restricted stock
Stock option plan
Number of shares of restricted stock granted	735,324
2013 Stock Incentive Plan \| Common stock
Stock option plan
Number of shares authorized	739,937
2009 Stock Incentive Plan
Stock option plan
Number of additional shares authorized		2,500,000
2009 Equity and Long Term Incentive Plan and 2013 Stock Incentive Plan \| Common stock
Stock option plan
Number of shares available for issuance		122,296
2013 Long Term Incentive Plan \| Common stock \| Minimum
Stock option plan
Annual increase in the number of shares on the first day of the fiscal year		2,500,000
Annual increase in the number of shares outstanding on the first day of the fiscal year (as a percent)		4.00%
2013 Long Term Incentive Plan \| Common stock \| Maximum
Stock option plan
Number of shares subject to outstanding awards		3,040,444

Stock award plan (Details 2) - Restricted stock	3 Months Ended
Stock award plan (Details 2) - Restricted stock	Mar. 31, 2014 $ / shares shares
Number of Shares
Balance at the beginning of the period (in shares) \| shares	1,110,226
Vested (in shares) \| shares	(359,450)
Forfeited (in shares) \| shares	(2,320)
Balance at the end of the period (in shares) \| shares	748,456
Weighted Average Grant Date Fair Value
Balance at the beginning of the period (in dollars per share) \| $ / shares	$ 10.68
Vested (in dollars per share) \| $ / shares	10.59
Forfeited (in dollars per share) \| $ / shares	10.59
Balance at the end of the period (in dollars per share) \| $ / shares	$ 10.73

The Company	3 Months Ended
The Company	Mar. 31, 2014
The Company
The Company	1. The Company PTC Therapeutics, Inc. (the Company or PTC) was incorporated as a Delaware corporation on March 31, 1998. The Company is a biopharmaceutical company focused on the discovery and development of orally administered, proprietary small-molecule drugs that target post-transcriptional control processes. The Company has devoted substantially all of its efforts to research and development, including clinical trials. The Company has not completed development of any drugs. The Company has not generated product revenue to date and is subject to a number of risks similar to those of other early stage companies, including dependence on key individuals, the difficulties inherent in the development of commercially usable products, the potential need to obtain additional capital necessary to fund the development of its products, and competition from other companies. As of March 31, 2014, the Company had an accumulated deficit of approximately $342.9 million. The Company has financed its operations to date primarily through a public offering in February 2014, its initial public offering in June 2013 (see note 6 below), private placements of its convertible preferred stock, collaborations, bank debt, convertible debt financings, grant funding and clinical trial support from governmental and philanthropic organizations and patient advocacy groups in the disease area addressed by the Company’s product candidates. The Company believes that its existing cash, cash equivalents, and marketable securities provide for sufficient resources to fund its currently planned operations through 2016.

Summary of significant accounting policies	3 Months Ended
Summary of significant accounting policies	Mar. 31, 2014
Summary of significant accounting policies
Summary of significant accounting policies	2. Summary of significant accounting policies The Company’s complete listing of significant accounting policies are described in note 2 of the notes to the Company’s audited financial statements as of December 31, 2013 included in the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission (SEC) on March 6, 2014 (2013 Form 10-K). There have been no changes to our accounting policies during the quarter. Basis of Presentation The accompanying unaudited financial information as of March 31, 2014 and for the three months ended March 31, 2014 and 2013 has been prepared by the Company, without audit, pursuant to the rules and regulations of the SEC. Certain information and footnote disclosures normally included in financial statements prepared in accordance with generally accepted accounting principles in the United States (GAAP) have been condensed or omitted pursuant to such rules and regulations. These interim financial statements should be read in conjunction with the Company’s audited financial statements as of December 31, 2013 and notes thereto included in the 2013 Form 10-K. In the opinion of management, the unaudited financial information as of March 31, 2014 and for three months ended March 31, 2014 and 2013 reflects all adjustments, which are normal recurring adjustments, necessary to present a fair statement of financial position, results of operations and cash flows. The results of operations for the three month period ended March 31, 2014 are not necessarily indicative of the results to be expected for the year ended December 31, 2014 or for any other interim period or for any other future year. Use of estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

Collaboration Revenue	3 Months Ended
Collaboration Revenue	Mar. 31, 2014
Collaboration Revenue
Collaboration Revenue	9. Collaboration Revenue On January 22, 2014, the Company announced the initiation of a Phase 1 clinical program in its spinal muscular atrophy collaboration with F. Hoffman-La Roche Ltd and Hoffman-La Roche Inc. (Roche) and the Spinal Muscular Atrophy Foundation which triggered a $7.5 million milestone payment from Roche. The Company considered this milestone event substantive because the applicable criteria of its revenue recognition policy would be satisfied and recorded it as collaboration revenue for the three months ended March 31, 2014.

Summary of significant accounting policies (Policies)	3 Months Ended
Summary of significant accounting policies (Policies)	Mar. 31, 2014
Summary of significant accounting policies
Basis of Presentation	Basis of Presentation The accompanying unaudited financial information as of March 31, 2014 and for the three months ended March 31, 2014 and 2013 has been prepared by the Company, without audit, pursuant to the rules and regulations of the SEC. Certain information and footnote disclosures normally included in financial statements prepared in accordance with generally accepted accounting principles in the United States (GAAP) have been condensed or omitted pursuant to such rules and regulations. These interim financial statements should be read in conjunction with the Company’s audited financial statements as of December 31, 2013 and notes thereto included in the 2013 Form 10-K. In the opinion of management, the unaudited financial information as of March 31, 2014 and for three months ended March 31, 2014 and 2013 reflects all adjustments, which are normal recurring adjustments, necessary to present a fair statement of financial position, results of operations and cash flows. The results of operations for the three month period ended March 31, 2014 are not necessarily indicative of the results to be expected for the year ended December 31, 2014 or for any other interim period or for any other future year.
Use of estimates	Use of estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

The Company (Details) - USD ($) $ in Thousands	Mar. 31, 2014	Dec. 31, 2013
The Company
Accumulated deficit	$ 342,896	$ 328,798

Fair value of financial instruments and marketable securities (Details) - USD ($) $ in Thousands	Mar. 31, 2014	Dec. 31, 2013
Financial assets and liabilities measured at fair value on recurring basis
Marketable securities	$ 130,730	$ 127,053
Recurring basis \| Total
Financial assets and liabilities measured at fair value on recurring basis
Marketable securities	130,730	127,053
Warrant liability	113	58
Recurring basis \| Significant other observable inputs (level 2)
Financial assets and liabilities measured at fair value on recurring basis
Marketable securities	130,730	127,053
Recurring basis \| Significant unobservable inputs (level 3)
Financial assets and liabilities measured at fair value on recurring basis
Warrant liability	$ 113	$ 58

Fair value of financial instruments and marketable securities (Details 2) - USD ($) $ in Thousands	Mar. 31, 2014	Dec. 31, 2013
Marketable securities accounted for as available-for-sale securities
Amortized Cost	$ 130,649	$ 126,982
Gross Unrealized Gains	117	102
Gross Unrealized Losses	(36)	(31)
Fair Value	130,730	127,053
Commercial paper
Marketable securities accounted for as available-for-sale securities
Amortized Cost	3,998	14,993
Gross Unrealized Gains	2	5
Fair Value	4,000	14,998
U.S. corporate debt securities
Marketable securities accounted for as available-for-sale securities
Amortized Cost	126,651	111,989
Gross Unrealized Gains	115	97
Gross Unrealized Losses	(36)	(31)
Fair Value	$ 126,730	$ 112,055

Fair value of financial instruments and marketable securities (Details 3) - USD ($) $ in Thousands	Mar. 31, 2014	Dec. 31, 2013
Marketable securities on the balance sheet
Total Marketable securities, Less Than 12 Months	$ 78,509	$ 69,157
Total Marketable securities, More Than 12 Months	52,221	57,896
Commercial paper
Marketable securities on the balance sheet
Total Marketable securities, Less Than 12 Months	4,000	14,998
U.S. corporate debt securities
Marketable securities on the balance sheet
Total Marketable securities, Less Than 12 Months	74,509	54,159
Total Marketable securities, More Than 12 Months	$ 52,221	$ 57,896

Other comprehensive income (loss) and accumulated other comprehensive items (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2014 USD ($)
Other comprehensive loss and accumulated other comprehensive items
Balance at the beginning of the period	$ 70
Other comprehensive income before reclassifications	10
Other comprehensive income	10
Balance at the end of the period	80
Unrealized Gains On Marketable Securities
Other comprehensive loss and accumulated other comprehensive items
Balance at the beginning of the period	70
Other comprehensive income before reclassifications	10
Other comprehensive income	10
Balance at the end of the period	$ 80

Capital structure (Details 2) - Warrants - Common stock	Mar. 31, 2014 $ / shares shares	Dec. 31, 2013 $ / shares shares
2014
Warrants
Warrant shares \| shares	1,428	1,428
Exercise price (in dollars per share) \| $ / shares	128.00	128.00
2017
Warrants
Warrant shares \| shares	6,250	6,250
Exercise price (in dollars per share) \| $ / shares	128.00	128.00
2019 and 2020
Warrants
Warrant shares \| shares	7,030	7,030
Exercise price (in dollars per share) \| $ / shares	128.00	128.00
2014
Warrants
Warrant shares \| shares	322	452
Exercise price (in dollars per share) \| $ / shares	2,520.00	2,520.00

Net loss per share (Details 2) - shares	3 Months Ended
Net loss per share (Details 2) - shares	Mar. 31, 2014	Mar. 31, 2013
Net loss per share
Total shares excluded from calculation	3,882,286	781,966
Stock Options
Net loss per share
Total shares excluded from calculation	3,133,830	46,642
Unvested restricted stock
Net loss per share
Total shares excluded from calculation	748,456	735,324

Stock award plan (Details 3) - USD ($) $ in Thousands	3 Months Ended
Stock award plan (Details 3) - USD ($) $ in Thousands	Mar. 31, 2014	Mar. 31, 2013
Share-based compensation expense recorded in the statement of operations
Share-based compensation expense	$ 3,705	$ 621
Unrecognized compensation cost	$ 40,100
Weighted average remaining service period for recognition of unrecognized compensation cost	2 years 10 months 17 days
Research and development
Share-based compensation expense recorded in the statement of operations
Share-based compensation expense	$ 1,944	257
General and administrative
Share-based compensation expense recorded in the statement of operations
Share-based compensation expense	$ 1,761	$ 364

Collaboration Revenue (Details) $ in Millions	Jan. 22, 2014 USD ($)
Collaboration agreement \| Roche and SMA Foundation \| Clinical development milestones
Collaboration Revenue
Milestone payment received from Roche	$ 7.5