Wal-Mart Stores Inc.'s probe of possible bribery in Mexico may prompt executive departures and steep U.S. government fines if it reveals senior managers knew about the payments and didn't take strong enough action, corporate governance experts said.

Best Buy's decline reflects a cultural shift that's reshaping the retail world. All big-box stores, and Best Buy in particular, thrived in an era when comparison shopping meant physically going from store to store.