Morgan Stanley analyst Manan Gosalia, in a report earlier this week, set a target price of $54 for First Republic shares in a best-case scenario.
"I have not considered or discussed anything having to do with blanket insurance or guarantees of deposits," she said.
The Morgan Stanley report considered that a potential extension of FDIC insurance could bring a majority of First Republic's customers back.
Even if it clinches a cash infusion, the lender will probably need to take losses on securities in its so-called held-to-maturity portfolio, the Morgan Stanley analysts wrote.
In the worst-case scenario, First Republic's shares would sink to just $1, Morgan Stanley analysts estimated.