Does Dow's bearish descent mean we all get sore head?

The Dow Jones Industrial Average's 21 percent retreat from a record may foreshadow more losses for the 112-year-old stock gauge, based on its performance in previous bear markets.

"I don't expect this to be the end," said Dean Gulis, part of a group that manages about $3 billion in Bloomfield Hills, Michigan, for Loomis Sayles & Co. "Stocks have been trending down now for basically a year. They're going to keep struggling for a while."

The Dow slipped into a bear market on Wednesday (local time) for the 12th time since 1962, according to Westport, Connecticut-based research firm Birinyi Associates Inc. Prior declines averaged 29 percent and lasted 322 days, Birinyi data show. The biggest was a 45 percent drop over 694 days starting in January 1973.