Earnings surprises, price reaction and value - By Aswath Damodaran

Professor Damodaran also attaches a link to his Apple valuation spreadsheet at the end of his post.

The earnings season is upon us and each company’s earnings announcement is eagerly awaited, traded upon and talked about. For widely followed companies like Apple, the obsession with what the next earnings report will deliver overwhelms any sensible assessment of what it means for the company. But is this obsession merited? Do earnings announcements have significant effects on value? If so, why? More importantly, can you make money off earnings announcements?