aibioPTC Therapeutics closes $550,000,000 convertible notes offering
Tickers PTCT
PTC Therapeutics sold $550,000,000 of 0.0% convertible senior notes due 2031 through Morgan Stanley & Co. LLC as representative of the initial purchasers. The initial conversion price is about $107.48 a share.
Key facts
- Company
- PTC Therapeutics, Inc. (NASDAQ: PTCT)
- News type
- Debt Financing
- Primary source
- PTC Therapeutics, Inc. 8-K (2026-06-18)
The notes and the indenture
PTC Therapeutics, Inc. (Nasdaq: PTCT) completed a private offering of $550,000,000 of 0.0% Convertible Senior Notes due 2031 on June 18, 2026. The sale followed a purchase agreement dated June 15, 2026 with Morgan Stanley & Co. LLC, as representative of the several initial purchasers. The initial purchasers exercised their option in full, adding $50,000,000 of notes.
The notes were issued under an indenture with U.S. Bank Trust Company, National Association, as trustee. They bear no regular interest, and their principal will not accrete. They may carry special interest only if the company fails to meet its reporting obligations under the indenture or if the notes are not freely tradeable. The notes mature on June 15, 2031 unless they are converted, redeemed or repurchased first.
The notes are the company's general unsecured senior obligations. They rank equally with its existing unsecured debt, including the 1.50% Convertible Senior Notes due 2026. They are structurally junior to all liabilities of the company's subsidiaries.
Conversion, redemption and default
The initial conversion rate is 9.3042 shares per $1,000 of principal, an initial conversion price of about $107.48 a share. Before March 15, 2031, holders can convert only in set circumstances, such as a stock price at or above 130% of the conversion price for 20 of 30 trading days in a quarter, or a trading price for the notes below 98% of their conversion value. From March 15, 2031 they can convert at any time. The company chooses whether to settle in cash, shares or both.
The company may not redeem the notes before June 20, 2029. After that it may redeem for cash at 100% of principal, if the stock has traded at 130% of the conversion price for 20 of 30 trading days. If a fundamental change occurs before maturity, holders can require repurchase at 100% of principal.
The company estimates net proceeds at approximately $535.5 million after the initial purchasers' discounts and commissions and estimated offering expenses. It is using approximately $328.8 million of that to repurchase for cash $222.0 million in principal of its existing 1.50% Convertible Senior Notes due 2026, in privately negotiated deals with certain holders. The rest is for general corporate purposes, which may include more repurchases of the existing notes.
Who is named
Morgan Stanley & Co. LLC acted as representative of the initial purchasers, whose individual names the 8-K does not give. U.S. Bank Trust Company, National Association is the trustee. The 8-K names no placement agent or advisor beyond that representative.
Sephience, the Censa payments and the company's own warnings
PTC's product Sephience, a treatment for phenylketonuria, was approved by the European Commission and by the FDA for children and adults. The company's annual report, filed February 19, 2026, says the approvals triggered $25.0 million and $32.5 million in milestone payments to former Censa securityholders. The annual report passage cited here gives no trial results for Sephience.
The Censa obligations are large. In a rights satisfaction agreement signed August 5, 2025, the company agreed to pay up to $250.0 million in upfront consideration, and it paid $225.1 million at closing. It also agreed to additional milestone payments of up to $100.0 million each, or $500.0 million in aggregate, tied to net sales thresholds, and the annual report puts each of five payments at about $90.0 million.
The annual report says plainly: "We will need to generate significant revenues to achieve and sustain profitability and we may never do so."
Losses, cash and the year-end position
Research and development expense was $455.2 million in 2025, down from $534.5 million in 2024. The company reported net income of $682.6 million for 2025, after a net loss of $363.3 million in 2024. Cash provided by operations was $711.2 million in 2025, compared with cash used in operations of $107.7 million in 2024.
The 8-K and the annual report passages cited here do not explain what drove the swing from a loss to a profit. At the end of 2024 the company held $779.7 million in cash and cash equivalents and $360.0 million in short-term investments.