McAfee reported Thursday that quarterly profit declined sharply, but still topped estimates as sales of its virus protection software rose, and said it plans to buy back a $750 million in stock.

Shares rose 3.4 percent to $32.80 after hours.

The security software maker said net income fell to $12.2 million, or 7 cents a share, in its fourth quarter ended Dec. 31, from $32.9 million, or 20 cents, a year earlier. Revenue rose 17 percent to $365.5 million.

It reported profit, excluding items, of 46 cents a share, while analysts expected profit of 45 cents on revenue of $343.3 million.

The company forecast first-quarter net income of 24 cents to 29 cents a share, excluding items of 42 cents to 47 cents a share, on revenue of $345 million to $360 million.

Analysts expect profit of 45 cents per share on revenue of $343 million.

On a conference call after the earnings report, McAfee Chief Executive Dave DeWalt said he is concerned about the economy. "I do worry a little bit about the macro climate, particularly consumers," he said.

For the full year, it forecast net income of $1.25 to $1.35 per share, excluding items of $1.85 to $1.95, on revenue of $1.43 billion to $1.525 billion.

Analysts expected full-year profit of $1.88 on revenue of $1.43 billion.

It wasn't immediately clear whether the analysts' estimates directly correlated to the company's forecasts.

DeWalt had previously said the board planned to authorize a buyback, and analysts were expecting a repurchase of about $500 million.

Shares closed at $31.73, down 1.6 percent, on the New York Stock Exchange.