Shares of Gartner Inc. hit a year-high on Tuesday after the information technology research firm posted better-than-expected second-quarter profit.

The company also raised its earnings and revenue forecast for the year, and said it will buy back $500 million in shares.

The stock reached $28.58 before giving up some of its gains. In midday trading, shares of Gartner added $2.45, or 9.6 percent, to $28.01, on volume nearly three times a typical day. Shares have risen steadily from a year-ago low of $15.84 and last peaked at $28.58 in June.

Late Monday, Gartner said its net income for the three months ended June 30 rose 17 percent to $20.1 million, or 20 cents per share, from $17.2 million, or 18 cents per share, in the 2009 second quarter. Excluding $3.6 million in acquisition costs, adjusted profit totaled 24 cents per share, Gartner said.

Revenue rose 14 percent to $314.2 million from $183.9 million last year, helped by higher research and consulting revenue. Its events segment saw revenue spike 75 percent to $29.3 million. Gartner said it held 21 events with 9,697 attendees during the quarter, compared with 14 events with 5,108 attendees in the 2009 period.

The results topped the average estimates of analysts polled by Thomson Reuters, who had forecast profit of 22 cents per share, on revenue of $306.6 million.

Based on the surge in event revenue, Gartner increased its full-year forecast to a range of $1.26 billion to $1.3 billion, up from its prior outlook for revenue of $1.25 billion to $1.29 billion.

Wall Street had been expecting full-year revenue of $1.27 billion, but several analysts raised estimates after the results, bringing the average forecast to $1.28 billion.

The company now expects adjusted profit to range from 99 cents to $1.11 per share, versus its prior guidance of 81 cents to 93 cents per share. Analysts, on average, project $1.05 per share profit for the year, with estimates ranging from $1.01 to $1.08.