Despite a rebound by financial stocks and a batch of merger news, the stock market was unable to put together a sustainable advance. Stocks finished with a broad-based loss, a bit above session lows.

Uncertainty in foreign indices fueled early losses in the headline indices. Financials were the focal point of the weakness, falling to a loss of 2.2%. The drop was short-lived, though. Financials rallied to a gain of 5.3%, but finished with a gain of 2.5%.

Though financials helped the broader market move into positive territory, the stock market was unable to break above the prior session's high and began trending lower to finish in the red.

Billionaire and famed value investor Warren Buffett seemed unsure about the short-term direction of the economy and the stock market during a CNBC interview, but remains confident in the long-term potential of the U.S.

Buffett suggested that Wells Fargo (WFC 9.97, +1.36), which is one of his holdings, will emerge from current doldrums with greater earnings power than ever. Shares of WFC provided leadership to the financial sector.

There have been no new tangible developments regarding solutions for the troubles of banks and financial companies, but traders remain mindful that congress is expected to hold meetings this week regarding mark-to-market accounting rules. Treasury will unveil further details regarding its plan to handle banks' toxic assets in coming weeks, according to Reuters.

Less than two months after Pfizer (PFE 12.63, -0.10) announced it will acquire Wyeth (WYE 40.76, -0.07) for nearly $68 billion in cash and stock, Merck (MRK 20.99, -1.75) and Schering-Plough (SGP 20.10, +2.47) announced they will merge their companies. The consolidation among major pharmaceutical companies comes as they look to fatten product pipelines and fend off generic competition.

Merck is proposing to pay Schering-Plough shareholders 0.5767 shares of MRK and $10.50 in cash for each share of SGP. Based on MRK's closing price last week, the deal is valued at $41.1 billion, or $23.61 per share of SGP.

Merck's offer hasn't altered its expectations for 2009. The company reaffirmed its earnings forecast, which ranges from $3.15 to $3.30 per share. Wall Street expects the company to earn $3.26 per share.

Aetna (AET 20.42, +0.20) announced it intends to reaffirm its 2009 guidance, which calls for earnings from $3.85 to $3.95 per share. The consensus estimate is pegged at $3.85 per share.

Meanwhile, reports indicate merger talks between Genentech (DNA 92.63, +1.77) and Roche are progressing toward a deal. As of this writing, Roche is expected to pay $95 for each share of Genentech.

Merger news didn't stop there, though. CNBC reported that Dow Chemical (DOW 6.32, -0.79) has agreed to pay $78 in cash for each share of Rohm & Haas (ROH 74.91, +11.11). However, subsequent reports indicated the two companies have not yet reached a deal, and trial proceedings are set for Tuesday morning. (Note: shares of both companies remain halted; the price quotes reflect the change in price prior to being halted)

Despite what would ordinarily be considered positive catalysts, neither the health care sector (-0.9%), the materials sector (-1.1%), nor the broader market celebrated the announcements.

Beyond financials, energy was the only other sector to close the session with a gain. Energy stocks advanced just 0.5%, largely due to a 3.5% gain in crude oil prices. Crude gained 3.5% to close at $47.10 per barrel amid speculation OPEC will further slash output when it meets March 15.DJ30 -79.89 NASDAQ -25.21 NQ100 -2.0% R2K -2.2% SP400 -0.9% SP500 -6.85 NASDAQ Adv/Vol/Dec 752/2.06 bln/1941 NYSE Adv/Vol/Dec 888/1.56 bln/2207