Plagued by market speculation that it could become the next Bear Stearns, Lehman Brothers has received a vote of confidence from Citigroup, which raised its rating on Lehman shares to a "buy."

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In a note headlined "Reality Will Trump Fear," Citigroup analyst Prashant Bhatia says that Lehman has "ample liquidity."

"With $34 billion in liquidity at the parent company, the ability to get access to over $200 billion in liquidity from the Fed's primary dealer credit facility, and its ability to tap the term auction facility, access to liquidity is a non-issue, he said.

In addition, he said, pointing to the diversity in the firm's earnings "We estimate that, write-downs aside, Lehman had its second best fixed-income trading quarter ever."

Shares of Lehman fell 9 percent on Thursday on rumors of a possible run on the bank. Activity in options to sell Lehman were active. OptionsMonster noted on Thursday that "The type of put buying seen is reminiscent of the put buying in Bear Stearns just before the axe fell."

Lehman said on Thursday that the liquidity rumors were unfounded, adding that, "We are suspicious that the rumors are being promulgated by short sellers of our stock that have an economic self-interest."