Thursday's Financial Winners & Losers

Citigroup's (C Quote) plunge, catalyzed by a couple of downgrades, helped to drag down both the financial sector and the broader market Thursday.

CIBC World Markets lowered Citi's rating to sector underperformer, saying the banking giant will need to raise significant cash in order to pad its currently thin capital ratio. That will weigh substantially on its stock price, said the analyst, and the bank may also have to cut its dividend. Credit Suisse, which cut the stock to neutral from outperform, also cited capital-related worries.

Citi shares took a 6.8% tumble to $38.54, which put heavy pressure on both the NYSE Financial Sector Index and on the KBW Bank Index. The former plunged around 276 points, or 2.9%, to roughly 9,135; the latter slid 4.3% to 98.9.

Another component of both trackers, Bank of America (BAC Quote), also got a CIBC downgrade to sector performer from sector outperformer on revenue concerns. And Merrill Lynch cut Swiss bank UBS (UBS Quote) to neutral from buy, citing the possibility of more subprime-mortgage-related writedowns. Shares fell 3.7% and 4.8%, respectively.

Credit Suisse (CS Quote), meanwhile, sank 5.1% to $64.25 after third-quarter income fell 11.3% from last year's continuing-operations earnings to about $1.12 billion (1.3 billion Swiss francs), or $1.02 a share. Revenue wilted 19% to $5.2 billion.

Radian Group (RDN Quote) yanked down the mortgage-insurance sector after posting a third-quarter loss of $704 million, or $8.78 a share, to reverse year-ago earnings of $1.36 a share. As expected, writedowns from its exposure to Credit Based Asset Servicing and Securitization (C-BASS), which focuses on subprime mortgages, took the single biggest bite out of its bottom line.