Stock prices for Google Inc, the world's largest internet search company, rose 13 per cent on Friday after it reported a huge surge in profits for the second quarter, dpa reported. Net earnings rose by 36 per cent to 2.51 billion dollars, the company said late Thursday. On a per share basis, profit was 8.74 dollars, nearly a dollar more than analysts had expected. Sales rose to 6.92 billion dollars, also topping estimates of 6.57 billion dollars expected by analysts surveyed by Bloomberg news. Google's main income stems from advertising, with companies paying a per-click price for the postings. Chief Executive Officer Larry Page, who succeeded Eric Schmidt in April, indicated that ad prices had risen by 12 per cent, a faster pace than the 8 per cent in last quarter, in a sign that companies were more willing to market their goods online.