Investor Duan Yongping disclosed Micron Technology (MU) holdings and recent options transactions on Xueqiu on Aug. 20. His records show that 100 previously sold $870 put options were exercised on Aug. 10, requiring him to buy 10,000 Micron shares for $8.7 million. On Aug. 11, he sold 100 Micron call options expiring Aug. 26 at $37.55 each, receiving about $375,500 in premiums. The records also show 100 $870 puts expired worthless on each of Aug. 12, Aug. 14 and Aug. 17. Duan said short-term option buyers are probably betting on an outcome, while sellers may resemble insurers or casino operators whose advantage depends on rules that control the odds. He said selling puts requires understanding the underlying business and its probability of success, and investors should not expect to win every trade but should avoid anything they do not understand.