In corporate news, Microsoft ( MSFT) agreed to make a $300 million investment for a 17.6% stake in a new Barnes & Noble ( BKS) subsidiary that will bring together the bookseller's digital and college businesses. Microsoft shares ticked up on the day while Barnes & Noble shares surged more than 50%. Shares of Monster Beverage ( MNST) soared during Monday's session following a Wall Street Journal report that said the company was in talks to be acquired by Coca Cola ( KO) but the stock ultimately finished marginally lower after Coke denied the report. Shares of Sunoco ( SUN) jumped 20% to $49.34 after pipeline operator Energy Transfer Partners agreed to buy the company for $5.35 billion. Also, NYSE Euronext ( NYX) said its first-quarter adjusted earnings declined 32%. The exchange saw a slowdown in trading, particularly in its derivatives trading unit, and was hit by costs associated with its failed merger with Germany's Deutsche Boerse. Adjusted profit in the quarter was 47 cents a share; analysts were looking for 48 cents. Shares fell about 5%. Warner Chilcott ( WCRX ), the drug maker, is weighing options including a possible sale after receiving interest from strategic and private-equity buyers, according to people with knowledge of the matter, Bloomberg reported. Shares surged 16%. Humana ( HUM), the health care company, reported first-quarter earnings Monday of $248 million, or $1.49 a share, down from year-earlier earnings of $315 million, or $1.86 a share. First-quarter earnings included a gain of 3 cents a share from previous medical claim reserves; year-earlier earnings included a gain of 31 cents a share. Humana was expected by analysts to report first-quarter earnings of $1.52 a share. Humana raised its full-year 2012 guidance to between $7.55 a share and $7.75 a share from a previous range of between $7.50 a share and $7.70 a share. Analysts were calling for earnings of $7.99 a share. The stock tumbled 8%. In commodity markets, the June crude oil contract fell 60 cents to settle at $104.87 a barrel on eurozone economic concerns. June gold futures settled flat at $1,664.20 an ounce, recovering from earlier lows. The benchmark 10-year Treasury was rising 5/32, diluting the yield to 1.923%. The dollar was rising by 0.1% against a basket of currencies, according to the dollar index.