Ford is slashing its stake in Mazda by nearly two-thirds, joining other struggling US automakers in a fire-sale of prized assets to stay afloat. Ford, which owns 33.4% of Mazda, will sell about a 20% stake, the companies said. The sale would net Ford $540 million based on Mazda's closing price today, barely a quarter of what it would have been worth a year ago. (More Ford stories.)