It was another tumultuous day on Wall Street. Here's what happened:

4:30 pm: Dow on track to post its worst month since 1931

With the bear market picking up steam with Monday's 3% slide, the Dow is nearing the completion of its worst month of trading since 1931. The blue-chip index, down 26.8% for the month of March, is on pace to notch its worst calendar month since September 1931, when it fell 30.7%.