Chesapeake (CHK, news, chart, volatility) gapped down and is off $2.88, or 14.2 percent, to $17.35 per share after the company issued a regulatory filing to sell 50 million shares at $15.82, a 22 percent discount to its closing price Wednesday. The natural gas producer also registered to sell $1 billion of stock for general corporate purposes. Investors seem to have been blindsided, as shares were up nearly 20 percent on the week before the news. In the options market, bullish sentiment had been building as well. 33,000 CHK calls and 7,600 puts traded Wednesday, including 6,615 December 20 calls.