This is the explanation, from a technical standpoint. Yesterday's close printed a very bullish candle right at major support, the 200dma. Many very experienced traders have sophisticated software that will show this bullish print, and then the technical day traders are all over it in the AM (today). Since IOC is not a very liquid stock, they drove the PPS up quickly, and took out a few shorts' stops in the process.
As soon as they (the daytraders) realize that their profits would top out (in this case today at about $77), they grab their profits and run. Then the rest of the day, the stock goes into a trading range.
That's what happened.....
IOC is very hard to borrow right now, especially if you are not a very large account. Some broker might have taken the borrow away from a smaller client to give to a larger client. This would force the little guy to buy to cover within 24-48 hours. Today looked like a forced buy-in to cover a short position. On a deal announcement, the shorts all have to go through the same small door to buy and exit.