Samsung Electro-Mechanics was the most heavily bought stock by Mirae Asset Securities clients in the top 1% by investment return over the past month, a group the brokerage calls "stock masters," as of 11 a.m. on the 10th. Samsung Electronics preferred shares and Samsung Biologics followed, while Samsung Electronics common shares, Korean Air and SK hynix led net selling. Samsung Electro-Mechanics traded at 882,000 won, up 4.63%, after falling 40.52% over the previous month. The buying followed a 6.85% overnight surge in the Philadelphia Semiconductor Index and a rally in Korean chip stocks, suggesting top traders were seeking a rebound in shares that had declined sharply. Samsung Electronics preferred shares rose 5.43% to 159,100 won, a discount of more than 20% to the common stock, after the company said on Oct. 29 that it would actively adjust the preferred-share proportion in future buybacks and retirements to boost corporate value. Samsung Biologics ranked third in net buying despite trading 2.78% lower at 1.468 million won. Hanwha Ocean and DL E&C ranked fourth and fifth among net buys. Samsung Electronics common shares rose 4.90% but moved to the top of the net-selling list, while Korean Air gained 10.31% to 32,100 won after NH Investment & Securities raised its target price to 41,000 won from 34,000 won. SK hynix rose 5.72% to 1.201 million won and ranked third in net selling for a second consecutive day. Mirae Asset publishes these client-trading statistics in real time, on a previous-day basis and over five days, while warning that they are informational only and that theme-related stocks can be highly volatile.