Investors have had little reason to be hopeful during the past two years as the economic news seems to get more depressing by the day. But lately, the stock market has turned optimistic and investors begin the week bracing themselves for any word that the good times may not last.

Stocks appear poised to open higher as Express Scripts Inc. (ESRX) agreed this morning to acquire Wellpoint Inc.'s (WLP) pharmacy benefits management business for $4.68 billion, proving that the once-moribund mergers and acquisitions market is showing signs of life.

Oil prices fell below $52 a barrel as International Energy Agency data shows demand dropping.

But all eyes will be on the financial sector earnings this week as investors see if optimistic words from their managements are backed up by actions.

Bank of America Corp. (BAC) has soared more than 63 percent on statements from Chief Executive Kenneth Lewis that the Charlotte-based bank was profitable in the first two months of the year. He also bragged that the company took too much federal bailout money. Similar comments were made by Citigroup Inc.'s (C) Vikram Pandit, whose beaten-down shares have soared 82 percent to a whopping $3.04.

JPMorgan Chase & Co. (JPM) and Wells Fargo & Co. (WFC) are both up around 40 percent while Goldman Sachs Group Inc. (GS) gained about 28 percent as optimism about the financial sector grows. Even General Electric Co. (GE), perhaps the least popular S&P component on Wall Street, is up 18 percent.

Investors will want proof that these companies are actually making money and not just in the black when every possible unpleasantness is ignored.