Knight Capital ( NITE) plunged more than 12% after an analyst with Sandler O'Neill said its "core" trade execution business showed signs of stalling in the quarter despite a reported 12% gain in fourth-quarter profits. Earnings came to 33 cents a share, excluding items, which beats the consensus by a penny, but the analyst noted that only 12 cents of the total derived from the firm's market-making division. Shares were losing $2.67 to $18.79.

Nasdaq Stock Market ( NDAQ) sank after the London Stock Exchange, in further defense against Nasdaq's $5.2 billion hostile bid for the British exchange, said it will boost its share buyback program by as much as $491 million. Shares were falling 99 cents, or 2.8%, to $34.46.

Sovereign Bancorp ( SOV) fell after it swung to a loss in the fourth quarter and sharply narrowed its full-year gains. The Philadelphia-based bank lost $129.4 million for the quarter, or 28 cents a share, compared with profits of $165.5 million, or 42 cents a share, a year ago. Full-year earnings came to $136.9 million, or 30 cents a share, compared with last year's $676.2 million, or $1.77 a share. Shares were down 65 cents, or 2.6%, to $24.36.

North Bay Bancorp ( NBAN) jumped after the Napa, Calif.-based regional bank agreed to be bought by Umpqua Holdings ( UMPQ) for a total stock-based value of about $156 million. North Bay shares were adding $4.18, or 13.9%, to $34.18. Portland, Ore.-based Umpqua was down 25 cents, or 0.9%, to $28.52.

Jefferies Group ( JEF) jumped after fourth-quarter profits topped Wall Street expectations. The New York-based investment broker said earnings jumped 19% to $55.8 million, or 38 cents a share. Analysts were looking for income to flatline with last year's 34-cent profit. Revenue rose 9% to $374.2 million from a year ago, beating the mean target by about $17.5 million. Shares were trading up $1.13, or 4%, to $29.48.

Webster Financial ( WBS) gained after the Connecticut-based bank said it earned $43.3 million in the fourth quarter, or 77 cents a share. This represents a drop from last year's $45.5 million, or 84 cents a share, but analysts were seeking 71 cents. Shares were adding $1.74, or 3.7%, to $48.59.