OTTAWA (AFP) ― BlackBerry co-founder Mike Lazaridis has boosted his stake in the troubled Canadian tech firm with the intention of making an acquisition bid, regulatory documents showed Thursday.

A document filed with the U.S. Securities and Exchange Commission said Lazaridis now has eight percent of BlackBerry shares and is working with another co-founder, Douglas Fregin, “to explore the possibility of submitting a potential joint bid” for the group.

The document said the two “are considering all available options” including “a potential acquisition of all the outstanding shares of the Issuer that they do not currently own, either by themselves or with other interested investors.”

The former BlackBerry executives have also hired Goldman Sachs Group Inc. and Centerview Partners LLC to help them study their options, according to the filing.

BlackBerry announced in August after a dismal year that it was looking for a suitor, among other strategic options.

The company that helped create a culture of mobile users glued to smartphones, but lost its luster as many have since moved to iPhones or devices using Google’s Android software, later said it had signed a letter of intent for a $4.7 billion buyout by Fairfax Financial Holdings Limited.

Fairfax, a Canadian firm headed by billionaire Prem Watsa, is already BlackBerry’s largest shareholder with approximately 10 percent of its shares.

Watsa resigned from BlackBerry’s board in August when the search for a suitor began.

But analysts and observers said the proposal was bait to elicit other bids.

Adding to the skepticism, BlackBerry shares have traded below Fairfax’s $9 per share offer since the company announced its intentions on Sept. 23.

BlackBerry shares were up 0.37 percent at $8.14 in late New York trade.