But on Friday, Best Buy said Schulze can make his offer between Feb. 1 and Feb. 28. The original proposal deadline was this Sunday, 60 days after the due diligence period started.
The Minneapolis company said the extension is in the best interest of shareholders and gives Schulze and his investor partners time to review Best Buy's full-year financial results.
Citi Investment Research analyst Kate McShane, who has a "Neutral" rating on Best Buy, said the probability of a deal appears "slim."
"We believe today's news shows that Mr. Schulze may be having difficulty finding financial backing from private equity firms," she wrote in a note to investors. "The extension will allow Mr. Schulze and potential partners to adjust their proposal post holiday results, which we believe could be disappointing."
A spokesman for Schulze declined to comment.
Best Buy Co. has been implementing a turnaround plan aimed at improving results as it faces tough competition from discounters and online retailers. In its most recent third quarter, it recorded a loss due to restructuring charges and continued weak sales.
Richard Schulze, 71, founded the company in 1966 and is its largest shareholder by far with a 20 percent stake. He has been considering a bid or selling his stake since resigning in June, following an investigation that led to the resignation of CEO Brian Dunn due to an inappropriate relationship with a female staffer.