What happened

Plug Power (PLUG -5.26%) stock plunged 4.6% in 9:45 a.m. EST trading on the Nasdaq this morning. The drop followed the company's public announcement that it will be expanding its partnership with Universal Hydrogen with the goal to accelerate development of a hydrogen fuel-cell airplane engine capable of flying over 600 miles without refueling. In addition, it somewhat less publicly warned investors that it is going to have to delay publishing its 10-K financial report. 

So what

Plug made the first announcement in a press release, noting that thanks to its recent raising of billions of dollars in cash through new stock issuances, it can now "enable Universal Hydrogen to complete the construction of a subscale aircraft powertrain by Q2 2021." Plug then plans to install the powertrain in a "40-60 passenger regional aircraft" and begin experimental flights with this aircraft in 2023, then begin flying it commercially in 2025.

Plug did not say which airline will fly the plane, or whether the company plans to enter the airline business itself.

It also predicted that by 2025, its green hydrogen products will become cost-competitive with jet fuel for powering airplanes. To first accelerate and then capitalize on this development, Plug says it "plans to build five regional green hydrogen facilities in the United States."  

Airplane flies over an H2 fuel tanker.

Image source: Getty Images.

Now what

That's the good news; here's the bad. Here's the reason why Plug stock is going down today:

At the same time as it was publishing its press release ballyhooing the above developments, Plug filed a form with the Securities and Exchange Commission (SEC), reminding the agency that for fiscal 2020, it has just become what the SEC calls a "large accelerated filer for the first time." For the first time, the company is now subject to rules requiring it to submit its 10-K annual reports within 60 days of wrapping up a financial year, rather than the 75 days it used to have. Plug had trouble getting its numbers in order in time to make the new deadline, however, and as a result "requires additional time to complete the procedures relating to its year-end reporting process, including the completion of the Company's financial statements and procedures relating to management's assessment of the effectiveness of internal controls."

Although Plug apparently hoped for the best, it turns out that "the Company is therefore unable to file the Form 10-K by March 1, 2021, the prescribed filing due date" -- and must ask for an extension.

Now, the company hastens to reassure that it "is working diligently to complete the necessary work," and it anticipates that its "full year 2020 results of operations will be consistent with those disclosed in the Company's press release furnished as Exhibit 99.1 to the Company's Current Report on Form 8-K filed with the Securities and Exchange Commission on February 25, 2021."

But even so, the delay, combined with the fact that the Feb. 25 8-k filing saw Plug losing $1.12 per share in Q4 -- a massive loss and much worse than expected -- seems to be giving investors a case of the jitters today, fuel cell-powered airplanes notwithstanding.