The News Corporation moved on Tuesday to reverse the accelerating drop in its stock price, announcing a program to repurchase $5 billion in shares.

Since last week, when a phone-hacking scandal involving one of the company’s British tabloids was revealed to be far more widespread than previously known, the company’s stock lost about 15 percent of its value. Investors, nervous that the widening controversy would imperil the company’s bid to acquire the parts of British Sky Broadcasting, or BSkyB, that it does not already own, have dumped shares over the last several days.