Red Hat Inc. shares plunged more than 10% in the extended session Thursday after the company issued weaker than expected second-quarter guidance. Red Hat stock closed down 2.2% to $165.65 during regular trading. The company reported first-quarter net income of $113.2 million, or 59 cents a share, compared with $75.3 million, or 41 cents a share, in the year-ago period. Adjusted earnings were 72 cents a share. Revenue rose to $813.5 million from $676.8 million in the year-ago period. Analysts surveyed by FactSet had estimated adjusted earnings of 68 cents a share on revenue of $807.5 million. For the second quarter, analysts model adjusted earnings of 89 cents a share and revenue of $855 million. The company said it expects second-quarter adjusted earnings of 81 cents a share on sales of $822 million to $830 million. Separately, Red Hat announced a $1 billion stock repurchase program to replace the existing program that expires June 30. Red Hat stock has gained 38% this year, with the S&P 500 index rising 3.5%.