The M&A market has caught fire with a series of jumbo corporate deals. Bidders claim that these are compelling strategic transactions that will create long-term value. But the real reason may be fear that shareholders are now focused on weak revenue prospects. Buying earnings is a way for companies to prevent share prices that low policy rates have inflated from falling back to earth. But confidence is still surprisingly fragile. A couple more big deal failures could slam the M&A market back into the freezer and take the equity markets with it.