Whenever a company delays a regulatory filing, particularly one involving quarterly or annual financial updates, some investors fear the worst. After all, such filings are a normal and expected aspect of the life of publicly traded businesses.

This explains the nearly 2% sell-off in SunPower (SPWR 5.85%) shares on Thursday. The solar energy company admitted in a brief regulatory filing that it'll be late in filing its latest set of fundamentals.

Annual report filing delayed

Anyone hoping to learn in-depth how SunPower did in 2023 will have to wait longer than expected. The company said the submission of its 10-K annual report would be delayed an indefinite period of time.

The solar energy sector mainstay said that this was due to restatements it had to make to the financial statements of recent quarterly and annual reports. It wrote in its Thursday filing that "As a result of the time and effort that was required to complete these restatements, the Company requires additional time to complete its financial statements preparation and review process for the fiscal year ended December 31, 2023."

It added that it cannot meet the prescribed deadline "without unreasonable effort or expense."

Although SunPower did not place a date in regard to timing, it did say it would file the 10-K "as soon as practicable."

The latest quarterly report wasn't exactly impressive

Despite its annual report hiccup, SunPower did divulge its fourth-quarter results; this occurred earlier in February. However, the company missed analyst estimates for both revenue and net loss for the period, and provided an update about its financing that raised concerns with investors. While solar has vast potential as an alternative source of energy, this is a company that needs a convincing win -- hopefully sooner rather than later.