The markets extended its losses during the midday with the Dow plummeting 229 points to 7901 as investors locked in profits in the financial services sector. Nasdaq skidded 57 points to 1615.

On the upside

Lazard Capital Markets upgraded Dendreon (Nasdaq: DNDN) after the biotechnology firm announced upbeat results from a Phase 3 clinical study of its prostate cancer treatment Provenge.

Although first quarter earnings for Halliburton (NYSE: HAL) tumbled as revenue fell, the results topped analyst estimates.

On the downside

BreitBurn Energy Partners' (Nasdaq: BBEP) borrowing base has been redetermined and the company suspended distributions to unitholders.

Sterne Agee downgraded SunTrust Banks (NYSE: STI).

McMoRan Exploration (NYSE: MMR) swung to a first quarter loss as revenue plunged amidst falling sales and retreating prices.

Revlon (NYSE: REV) majority shareholder MacAndrews & Forbes Holdings requested that the cosmetics company convert Class A shares into preferred stock.

In the broad market, declining issues overwhelmed advancers by a margin of nearly 8 to 1 on the NYSE and by more than 9 to 2 on Nasdaq. The Russell 2000 which tracks small cap stocks slumped 24 points to 455.