Citigroup ( C) slipped after the New York-based financial services behemoth reported a 23% decline in third-quarter profit and flat revenue. In the quarter, the nation's biggest bank earned $5.5 billion, or $1.10 a share, compared with $7.14 billion, or $1.38 a share, in the year-ago period. Total revenue was down a hair from a year ago to $21.42 billion. Profit from continuing operations rose 6% to $5.3 billion, or $1.06 a share. On that basis, Citigroup exceeded the Thomson Financial consensus estimate of $1.03 a share by 3 cents. But revenue came in slightly below the target estimate of $21.63 billion. Shares slipped 47 cents, or nearly 1%, to $49.72. Greenhill ( GHL) sank after the New York-based investment bank posted lower third-quarter earnings. The company posted income of $14.2 million, or 48 cents a share, compared with $17.8 million, or 58 cents a share, a year ago. Revenue dropped 13% from a year ago to $57.6 million. Wall Street was looking for earnings of 51 cents a share on revenue of $60.8 million. Shares dropped $4.11, or 5.8%, to $66.52. The Nasdaq Stock Market ( NDAQ) gained after posting a 69.7% gain in third-quarter profit, as revenue nearly doubled at the exchange. In the quarter, Nasdaq earned $30.2 million, or 22 cents a share, up from $17.8 million, or 16 cents a share, a year ago. Revenue rose 83% to $403 million. Analysts, as surveyed by Thomson Financial, were predicting earnings of 16 cents a share on revenue of $394 million. Shares gained 86 cents, or 2.5%, to $35.86.