Marissa Mayer took on a Sisyphean task when she became Yahoo chief executive in 2012. Failure shouldn't have spelled career disaster. But a catalog of missteps has changed that. Mayer has probably squandered her chance of another prominent corner office.
Four years ago, Mayer's arrival brought hope to a company that was churning through CEOs and had caught the unwanted attention of activist investor Dan Loeb. The former Google engineer was a rarity: a woman with the background, tech skills and style to put hoodie-wearing dudes to shame.