PLUG POWER INC Debt Disclosure
13. Convertible Senior Notes
6.75% Convertible Senior Notes
On November 21, 2025, the Company issued $431.3 million aggregate principal amount of 6.75% Convertible Senior Notes, including the exercise in full of the initial purchasers’ option to purchase up to an additional $56.3 million principal amount of the notes. The notes were issued pursuant to an indenture, dated November 21, 2025 (the “Indenture”).
The notes are general unsecured obligations of the Company and rank senior in right of payment to all of its future indebtedness that is expressly subordinated in right of payment to the notes, equal in right of payment to all of its existing and future liabilities that are not so subordinated, effectively junior to all of its secured indebtedness, to the extent of the value of the assets securing such indebtedness, and structurally junior to all indebtedness and other liabilities of its subsidiaries. The notes bear interest at a rate of 6.75% per year. Interest is payable semi-annually in arrears on June 1 and December 1 of each year, beginning on June 1, 2026. The notes mature on December 1, 2033, unless earlier repurchased, redeemed or converted.
The notes may not be converted prior to the earlier of (i) February 28, 2026 and (ii) the “reserved share effective date” (as defined in the Indenture) (such earlier date, the “conversion limit end date”). On or after the conversion limit end date, the notes are convertible at the option of the holders at any time prior to the close of business on the second scheduled trading day immediately preceding the maturity date. Upon conversion, the Company will pay or deliver, as the case may be, cash, shares of the Company’s common stock, or a combination of cash and shares of common stock, at the Company’s election, in the manner and subject to the terms and conditions provided in the Indenture; provided that unless and until the reserved share effective date occurs, the Company will settle conversion of notes solely with cash.
The conversion rate of the notes will initially be 333.3333 shares of common stock per $1,000 principal amount of notes, which is equivalent to an initial conversion price of approximately $3.00 per share of common stock. The initial conversion price of the notes represents a premium of approximately 40% over the last reported sale price of $2.14 per share of common stock on The Nasdaq Capital Market on November 18, 2025. The conversion rate for the notes is subject to adjustment under certain circumstances in accordance with the terms of the Indenture. In addition, following certain corporate events that occur prior to the maturity date or if the Company delivers a notice of redemption in respect of the notes, the Company will, in certain circumstances, increase the conversion rate of the notes for a holder who elects to convert its notes in connection with such a corporate event or convert its notes called (or deemed called) for redemption during the related redemption period (as defined in the Indenture), as the case may be.
The Company may not redeem the notes prior to December 6, 2028. The Company may redeem for cash all or any portion of the notes (subject to certain limitations), at its option, on or after December 6, 2028 and prior to the 26th scheduled trading day immediately preceding the maturity date, if the last reported sale price of the common stock has been at least 130% of the conversion price for the notes then in effect for at least 20 trading days (whether or not consecutive) during any 30 consecutive trading day period (including the last trading day of such period) ending on, and including, the trading day immediately preceding the date on which the Company provides notice of redemption at a redemption price equal to 100% of the principal amount of the notes to be redeemed, plus accrued and unpaid interest to, but excluding, the redemption date. However, the Company may not redeem less than all of the outstanding notes unless at least $50.0 million aggregate principal amount of notes are outstanding and not called for redemption as of the time we send the related notice of redemption (and after giving effect to the delivery of such notice of redemption).
Holders of notes may require the Company to repurchase for cash all or any portion of their notes on December 6, 2029 at a repurchase price equal to 100% of the principal amount of notes to be repurchased, plus accrued and unpaid interest to, but excluding, December 6, 2029. In addition, if the Company undergoes a fundamental change (as defined in
the Indenture), then, subject to certain conditions and except as set forth in the Indenture, holders may require the Company to repurchase for cash all or any portion of their notes at a repurchase price equal to 100% of the principal amount of the notes to be repurchased, plus accrued and unpaid interest to, but excluding, the fundamental change repurchase date.
The Indenture includes customary covenants and sets forth certain events of default after which the notes may be declared immediately due and payable and sets forth certain types of bankruptcy or insolvency events of default involving the Company after which the notes become automatically due and payable. In case of certain bankruptcy and insolvency-related events of default with respect to the Company, the principal of, and accrued and unpaid interest on, all of the then outstanding notes shall automatically become due and payable. As of December 31, 2025, the Company is in compliance with all debt covenants associated with the 6.75% Convertible Senior Notes.
The offering price of the notes was 95% of the principal amount of notes. The net proceeds from the 6.75% Convertible Senior Notes was $400.0 million after deducting the initial purchasers’ discounts and commissions and offering expenses payable by the Company. The Company used net proceeds from the 6.75% Convertible Senior Notes to fully repay the outstanding principal amount of its 15.00% Secured Debenture and to repurchase $138.0 million aggregate principal amount of the Company’s 7.00% Convertible Senior Notes. See Note 14, “Long Term Debt,” for further information. There were no conversion of the 6.75% Convertible Senior Notes during the year ended December 31, 2025.
The change in the carrying amount of the 6.75% Convertible Senior Notes for the year ended December 31, 2025 was as follows (in thousands):
Fair value of principal received at issuance | $ | 399,984 | |
Change in fair value of the convertible senior note | 30,608 | ||
Amortization of discount | 422 | ||
Ending balance as of December 31, 2025 | $ | 431,014 |
The following table summarizes the total interest expense and effective interest rate related to the 6.75% Convertible Senior Notes during the year ended December 31, 2025 (in thousands, except for the effective interest rate):
Year ended | ||
December 31, 2025 | ||
Interest expense | $ | 3,110 |
Amortization of discount | 422 | |
Total | $ | 3,532 |
Effective interest rate | 7.7% | |
6.00% Convertible Debenture
On November 11, 2024, the Company entered into the Debenture Purchase Agreement pursuant to which the Company issued to Yorkville the 6.00% Convertible Debenture in exchange for the payment of $190.0 million. The 6.00% Convertible Debenture was issued in a private placement in reliance upon an exemption from registration provided by Section 4(a)(2) of the Securities Act. The 6.00% Convertible Debenture ranked pari passu in right of payment with all other outstanding and future senior indebtedness of the Company.
The 6.00% Convertible Debenture was fully settled during 2025. The Company incurred losses on extinguishment of convertible debt instruments and debt of $9.1 million during the year ended December 31, 2025.
The change in the carrying amount of the 6.00% Convertible Debenture for the year ended December 31, 2025 was as follows (in thousands):
Beginning balance as of December 31, 2024 | $ | 173,150 | |
Loss on extinguishment of convertible debenture | 5,295 | ||
Amortization of discount | 957 | ||
Change in fair value of the convertible debenture | (1,902) | ||
Payments of principal settled in cash | (127,500) | ||
Payment of principal settled in common stock | (50,000) | ||
Ending balance as of December 31, 2025 | $ | — |
The following table summarizes the total interest expense and effective interest rate (prior period only) related to the 6.00% Convertible Debenture during the years ended December 31, 2025 and 2024 (in thousands, except for the effective interest rate):
Year ended December 31, | |||||
2025 | 2024 | ||||
Interest expense | $ | 2,473 | $ | 1,596 | |
Amortization of discount | 957 | 613 | |||
Total | $ | 3,430 | $ | 2,209 | |
7.00% Convertible Senior Notes
On March 20, 2024, the Company entered into separate, privately negotiated exchange agreements with certain holders of the Company’s outstanding 3.75% Convertible Senior Notes pursuant to which the Company exchanged $138.8 million in aggregate principal amount of the 3.75% Convertible Senior Notes, and accrued and unpaid interest of $1.6 million on such notes to, but excluding, March 20, 2024, for $140.4 million in aggregate principal amount of the Company’s new 7.00% Convertible Senior Notes due 2026, in each case, pursuant to the exemption from registration provided by Section 4(a)(2) under the Securities Act. Following the exchange, approximately $58.5 million in aggregate principal amount of the 3.75% Convertible Senior Notes remained outstanding with terms unchanged.
This transaction was accounted for as an extinguishment of debt. As a result, the Company recorded a loss on extinguishment of debt of $14.0 million in the consolidated statements of operations during the first quarter of 2024. Loss on extinguishment of debt arises from the difference between the net carrying amount of the Company’s debt and the fair value of the assets transferred to extinguish the debt.
In November 2025, the Company used net proceeds from the 6.75% Convertible Senior Notes to repurchase $138.0 million aggregate principal amount of the 7.00% Convertible Senior Notes in addition to $4.6 million of accrued interest. The Company incurred losses on extinguishment of convertible debt instruments and debt of $8.9 million during the year ended December 31, 2025. There were no conversions of the 7.00% Convertible Senior Notes during the years ended December 31, 2025 and 2024.
As of December 31, 2025, the 7.00% Convertible Senior Notes consisted of the following (in thousands):
| December 31, 2025 | | December 31, 2024 | |||
Principal amounts: | ||||||
Principal | $ | 2,413 | $ | 140,396 | ||
Unamortized debt premium, net of offering costs(1) | 170 | 7,514 | ||||
Net carrying amount | $ | 2,583 | $ | 147,910 | ||
| (1) | Included in the consolidated balance sheets within convertible senior notes, net and amortized over the remaining life of the notes using the effective interest rate method. |
The following table summarizes the total interest expense and effective interest rate related to the 7.00% Convertible Senior Notes during the years ended December 31, 2025 and 2024 (in thousands, except for the effective interest rate):
Year ended December 31, | |||||
2025 | 2024 | ||||
Interest expense | $ | 8,725 | $ | 7,687 | |
Amortization of premium | (4,833) | (4,085) | |||
Total | $ | 3,892 | $ | 3,602 | |
Effective interest rate | 3.0% | 3.0% | |||
3.75% Convertible Senior Notes
On May 18, 2020, the Company issued $200.0 million in aggregate principal amount of 3.75% Convertible Senior Notes due June 1, 2025 in a private placement to qualified institutional buyers pursuant to Rule 144A under the Securities Act. On May 29, 2020, the Company issued an additional $12.5 million in aggregate principal amount of 3.75% Convertible Senior Notes. On March 12, 2024, the Company exchanged $138.8 million in aggregate principal amount of the 3.75% Convertible Senior Notes for $140.4 million in aggregate principal amount of the Company’s new 7.00% Convertible Senior Notes due 2026. Following the exchange, approximately $58.5 million in aggregate principal amount of the 3.75% Convertible Senior Notes remained outstanding with terms unchanged.
During the year ended December 31, 2025, the Company paid cash of $59.6 million, which included $58.5 million to retire the remaining outstanding principal and $1.1 million to pay the remaining accrued interest, to fully settle the 3.75% Convertible Senior Notes.
The following table summarizes the total interest expense and effective interest rate (prior periods only) related to the 3.75% Convertible Senior Notes for the years ended December 31, 2025, 2024 and 2023 (in thousands, except for effective interest rate):
Year ended December 31, | ||||||||
2025 | | 2024 | | 2023 | ||||
Interest expense | $ | 914 | $ | 3,335 | $ | 7,546 | ||
Amortization of debt issuance costs | 189 | 642 | 1,345 | |||||
Total | $ | 1,103 | $ | 3,977 | $ | 8,891 | ||
About Debt Disclosures
Debt disclosures detail a company's borrowing structure — the types of instruments, interest rates, maturity schedule, and covenant restrictions that define its financial obligations and flexibility. This section is essential for assessing refinancing risk, interest rate exposure, and the margin of safety against financial distress.
Key signals: the maturity schedule reveals concentration risk — large maturities within 1-2 years during tight credit markets can force dilutive refinancing or asset sales. Compare the fair value of debt against carrying amount to gauge whether the market views the company's credit risk differently than the balance sheet suggests. Watch covenant compliance disclosures for tightening cushions, especially leverage and interest coverage ratios. Variable-rate debt exposure quantifies sensitivity to interest rate changes. Secured versus unsecured mix affects recovery rates and future borrowing capacity. Compare net debt-to-EBITDA against industry peers and covenant limits to assess financial health.