TORONTO - One of BlackBerry's largest shareholders has made a multibillion-dollar offer for the troubled smartphone maker hinged on several conditions that make the outcome anything but certain.

A letter of intent to acquire the Waterloo, Ont.,-based company in a deal that values the company at US$4.7 billion is being led by Canadian investment firm Fairfax Financial (TSX:FFH) and includes a consortium of others who have not been identified.

But it's only a tentative agreement to take the company private that could be sidelined by a variety of factors, and that has some analysts concerned.

"They're just trying to buy themselves some more time here," said MKM Partners analyst Mike Genovese. "This does not read like an actual deal; this is an announcement to stem the bleeding and buy some time."

It's "crazy that they would do a letter of intent before doing due diligence," added Genovese.

At first glance, the move by Fairfax, which owns about 10 per cent of BlackBerry common shares, may seem like a vote of confidence in the company's future.

But the letter of intent, filed with the U.S. Securities and Exchange Commission, outlines various ways that Fairfax could exit the deal with a hefty payout, or step away if it deems the transaction unattractive.

Fairfax could back out if it's not satisfied with its due diligence on BlackBerry's finances or if it doesn't receive the financial backing it needs, according to the public release.

And, under the agreement, Fairfax would benefit from break fees associated with other bidders who might emerge in the coming months with a better deal, or from a transaction that materializes within six months after the due diligence wraps up in early November.

"We have devoted substantial time, resources and energy to studying the company," writes Fairfax president Paul Rivett in a letter to BlackBerry's special committee formed to look at its strategic options.

"We believe our offer provides and extremely compelling combination of attractive and certain value for shareholders."

In the meantime, what the announcement has done is slow the dramatic decline in BlackBerry's stock price, which tumbled 16 per cent on Friday when the company announced it anticipated a near billion-dollar loss for the second quarter on poor sales of its handsets.

The share decline continued on Monday until the BlackBerry-Fairfax pact was announced, which helped the company's stock (TSX:BB) end flat on the Toronto Stock Exchange at $9.08, and ahead 9.5 cents to US$8.82 on the Nasdaq where it trade under the symbol (Nasdaq:BBRY).

Analyst Troy Crandall of Montreal investment firm MacDougall, MacDougall and MacTier said the tentative deal is positive for shareholders because "it relieves the uncertainty and volatility."

"It's far from a done deal," the Montreal-based analyst added.

BlackBerry has been struggling to maintain a hold on both its business users and average consumers. Both have turned increasingly to competitors like Apple's iPhone, which posted record sales of its latest devices over the weekend. The iPhone has also become an increasingly popular phone for business users.