BlackBerry co-founders Mike Lazaridis and Douglas Fregin are looking at making a potential takeover bid for the troubled smartphone maker.

According to documents filed with the U.S. Securities and Exchange Commission on Thursday, the two are "interested in pursuing a joint bid" with "the goal of stabilizing and ultimately reinventing the company."

The filing with the regulator said Lazaridis and Fregin are "considering all available options with respect to their holdings of the shares, including, without limitation, 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."

No financial details of any potential offer were included in the filing.

BlackBerry has struggled this year as sales of its latest smartphones failed to catch fire. In August, the Waterloo, Ont., company launched a strategic review to explore its options including the possible sale or break up of its operations.

Fairfax Financial (TSX:FFH), BlackBerry's largest shareholder, has made a conditional takeover bid worth US$9 per share and values the company at US$4.7 billion.

BlackBerry shares climbed five cents to close at C$8.49 on the Toronto Stock Exchange.

Carmi Levy, an independent technology analyst, said from an investor's perspective, it was "nothing but good news" that Lazaridis appeared to be seriously interested in making an offer for BlackBerry.

"The worst case scenario for BlackBerry was they would hold a sale and nobody would come, now clearly the lineup is starting to form," he said.

"It is still a small lineup, but a lineup all the same."

Together, Lazaridis and Fregin own roughly an eight per cent stake in BlackBerry, while Fairfax holds about 10 per cent.

Lazaridis served as president, co-chief executive and co-chairman of BlackBerry before he stepped aside in January 2012. Fregin helped Lazaridis found the company formerly known as Research In Motion and served as vice-president of operations before he left.

Lazaridis and Fregin have agreed to work together exclusively on any potential deal, not sell their shares and share the costs.

Under the agreement between the two men, Lazaridis will take the lead in developing a strategy, subject to approval by Fregin, in dealing with BlackBerry, potential investors and the media. Lazaridis declined to comment when contacted Thursday.

Analysts say the Fairfax offer is hinged on several conditions that make it far from a done deal.

Levy said the interest by Lazaridis will prompt Fairfax to move more decisively to get its consortium and financing in order.

"It doesn't fundamentally change things for Fairfax, but it certainly does raise the temperature and give it a much harder deadline than it had before," he said.

The Fairfax consortium is expected to complete its due diligence by Nov. 4. Until then, BlackBerry is allowed to actively solicit and evaluate rival offers.

BlackBerry said Thursday it was "conducting a robust and thorough review of strategic alternatives."

"We do not intend to disclose further developments with respect to the process until we approve a specific transaction or otherwise conclude the review of strategic alternatives," BlackBerry said in a statement.

Reports have suggested other companies possibly interested in taking a run at BlackBerry may include Google, Cisco, SAP, Microsoft and Cisco.

BlackBerry chief executive Thorsten Heins is working through what he's described as a three-stage plan to return the company to profitability.

The company recently announced a plan to cut about 40 per cent of its global workforce, or 4,500 jobs, as a way to save money. On Thursday, it announced it was closing its offices in the Halifax area, eliminating more than 300 jobs as part of an effort to cut costs.

A class-action lawsuit was also filed Thursday at the Ontario Superior Court on behalf of all Canadian BlackBerry shareholders.

In a statement, the Merchant Law Group LLP said the suit was on behalf of shareholders who purchased the stock between Sept. 27, 2012 and Sept. 20, 2013.

The lawsuit alleges the company and its senior management "knowingly or negligently misrepresented" that the BlackBerry 10 smartphones had been well received by customers and in a "strong financial position," according to a news release.

The representative plaintiff reportedly lost $55,000 after buying BlackBerry shares in the last year.

None of the allegations have been proven in court and BlackBerry was not immediately available to comment on the dispute.

Last month, BlackBerry booked a US$965-million loss for the second quarter of fiscal 2014, mostly due to a writedown of inventory.