Jackson said the falling share price showed that investors are dubious that Ontario Teachers' or other Canadian pension funds can be convinced to take part.
The Globe and Mail said Watsa was pitching the acquisition as a leveraged buyout that would be financed with more than $3 billion in bank loans, $1 billion in equity from institutions and Fairfax's nearly 10 percent stake in BlackBerry.
Bernstein analyst Pierre Ferragu said he doubted financial sponsors would be comfortable with $3 billion of debt, given the only collateral BlackBerry could offer is its patent portfolio, which he valued between $800 million and $1.5 billion.
"We believe the Fairfax initiative is unlikely to come to fruition and see the next valuation floor for the stock at $5," he wrote in a note to clients.