BlackBerry co-founder Mike Lazaridis, who is likely just as responsible for BlackBerry’s early success as he is for its collapse, on Thursday filed a Schedule 13D with the U.S. Securities and Exchange Commission revealing that he recently increased his stake in the company. Lazaridis had previously held a 5.7% stake in BlackBerry, and he now owns 8% of the company. The document also reveals that Lazaridis and fellow BlackBerry co-founder Douglas Fregin have entered into an agreement to “explore the possibility of submitting a potential joint bid” for BlackBerry, which is still on the ropes as rumors swirl that Fairfax Financial will not be able to secure funding for its proposed $4.7 billion buyout. BlackBerry shares spiked roughly 1% to $8.19 on the news after having been hovering in the red around $8.06 all morning.