Stock exchanges are supposed to have mechanisms to shut down waves of panicked selling that could be triggered by computerized trading glitches, but that apparently didn’t happen in New York amid fears of a European debt crisis.

The market teetered wildly on Thursday, and was not much more stable on Friday, with prices for some stocks diverging sharply on the NYSE and Nasdaq. The New York Stock Exchange put in a “circuit breaker” mechanism in the wake of the computerized trading-triggered sell-off that occurred on Oct. 19, 1987, also known as Black Monday. While that may helped NYSE officials pause the trading on their exchange on Thursday, the more electronic stock exchanges like the Nasdaq were still going full tilt, allowing prices to gyrate erratically. Even normally stable stocks like Procter & Gamble and Accenture had their prices suddenly plummet.

Speculation over the cause of the tumultuous trading activity included an errant trader who had mistakenly typed in "billions" instead of "millions" (something I must admit I have done, but without nearly as much effect), to concerns over Greek protests of austerity measures, and continuing progress of the financial regulatory reform measure in Washington.

Indeed, the financial regulatory reform bill seems to be advancing, with two Republican senators, Olympia Snowe of Washington and Charles Grassley of Iowa, joining Democrats in voting Thursday to allow the Consumer Financial Protection Bureau provision to be included relatively unscathed. Whatever effect that move may have had on Wall Street is anybody’s guess. But the impact of the electronic exchanges on exacerbating the reverberations of a panicked sell-off may be a matter that Congress will want to look into, and perhaps include in an amendment while the legislation is apparently still in play.

The SEC and the Commodity Futures Trading Commission have said they are reviewing the unusual trading activity and working with the exchanges to take the appropriate steps. Whatever those steps are, it’s likely that Wall Street traders will find a way to get around them.