Updated from 11:03 a.m. EDT

OfficeMax ( OMX) was among the NYSE's losers Thursday, as shares tumbled 15.5% after the office-supplies retailer posted first-quarter results that fell short of expectations.

The company earned $57.5 million, or 76 cents a share, on revenue of $2.44 billion. Excluding items, the company earned $59.7 million, or 77 cents a share. Analysts polled by Thomson Financial expected earnings of 93 cents a share on revenue of $2.46 billion. During the year-earlier quarter, the company reported adjusted earnings of $55.7 million, or 77 cents a share, on revenue of $2.42 billion. Shares closed down $7.67 to $41.79.

Tesoro ( TSO) fell 7.2% after the oil refiner posted disappointing first-quarter earnings. The company earned $116 million, or $1.67 a share, on revenue of $3.88 billion. Analysts expected earnings of $1.86 a share on revenue of $4.07 billion. During the year-earlier quarter, the company earned $43 million, or 61 cents a share, on revenue of $3.88 billion. Shares closed down $8.88 to $114.95.

Shares of Emergency Medical Services ( EMS) jumped 10.1% after the provider of ambulance and emergency medical services posted better-than-expected first-quarter results. The company earned $16.6 million, or 39 cents a share, on revenue of $523.3 million. Excluding items, the company earned 42 cents a share. Analysts expected earnings of 26 cents a share on revenue of $504.2 million. During the year-earlier period, the company earned $7.3 million, or 17 cents a share, on revenue of $469.1 million.

Looking ahead, the company now sees full-year earnings of $1.30 to $1.37 a share, up from an earlier forecast of $1.11 to $1.18 a share. Analysts project earnings of $1.17 a share. Shares closed up $3.39 to $36.86.

Unum Group ( UNM) climbed 9.7% after the insurance company posted first-quarter earnings that were better than expected. The company posted an operating profit of $174.6 million, or 50 cents a share, on revenue of $2.6 billion. Analysts expected earnings of 45 cents a share. During the year-earlier quarter, the company earned $129.2 million, or 40 cents a share, on revenue of $2.6 billion.

Looking ahead, Unum now sees full-year operating earnings of $1.91 to $1.95 a share, up from an earlier forecast of $1.83 to $1.87 a share. Analysts project earnings of $1.86 a share. Shares closed up $2.41 to $27.33.

Shares of Blount International ( BLT) tumbled 11.3% after the maker of industrial and power equipment posted first-quarter results that fell below expectations. The company earned $4.7 million, or 10 cents a share, on revenue of $144 million. Analysts expected earnings of 17 cents a share on revenue of $156.3 million. "This year's first-quarter results were adversely impacted by weak conditions in the North American timber markets," the company said. During the year-earlier quarter, the company earned $8.4 million, or 18 cents a share, on revenue of $163.8 million.

Looking ahead, Blount sees full-year revenue of $630 million to $655 million. Analysts project revenue of $638.9 million. Shares closed down $1.62 to $12.68.

NYSE volume leaders included Advanced Micro Devices ( AMD), up 6 cents to $13.69; Avon Products ( AVP), down 13 cents to $40.89; General Motors ( GM), down $1.75 to $30.69; EMC ( EMC), up 16 cents to $15.35; General Electric ( GE), up 3 cents to $37.34; Ford ( F), up 2 cents to $8.19; and Pfizer ( PFE), up 27 cents to $26.87.

Nasdaq volume leaders included Symantec ( SYMC), up 88 cents to $19.05; Intel ( INTC), down 8 cents to $21.74; Charter Communications ( CHTR), up 12 cents to $3.39; Microsoft ( MSFT), up 36 cents to $30.97; JDSU ( JDSU), down $2.31 to $14.33; Sun Microsystems ( SUNW), up 3 cents to $5.18; Level 3 Communications ( LVLT), up 20 cents to $5.62; and Cisco Systems ( CSCO), up 3 cents to $27.70.