General Motors shares hit 52-week low

Shares of General Motors Corp. are tumbling on a drop in the overall market and an ongoing strike at one of its key suppliers.

In heavy afternoon trading, GM shares fell $1, or 5.2 percent, to $18.22, after plummeting as low as $17.47 earlier in the day and easily passing its previous 52-week low of $19.

The broader market dropped Monday, before rising later in a day of volatile trading, reeling on news of JPMorgan Chase & Co.'s plans to buy rival investment bank Bear Stearns Cos. in a deal backed by the government.