The (relatively) gradual rebound in price suggests the trades actually happened. It's not a removable discontinuity, so to speak. And, frankly, if you were cod

The (relatively) gradual rebound in price suggests the trades actually happened. It's not a removable discontinuity, so to speak. And, frankly, if you were coding an automated trading system, it wouldn't be that unreasonable to write a "sell at any price" algorithm that doesn't cover the eventuality that a stock with a market cap as large as these might have literally no bids higher than $0.00. (My highly speculative amateur theory is that this is what actually happened: The NYSE froze trading on these stocks for an extremely brief period, as it did with many stocks today, and a handful of automated trading systems scrambled to electronic exchanges, where volumes were low enough that a $0.00 bid issued by some cleverly well-prepared hedge fund was the best around.)