Even quarterly operating profit exceeding 100 trillion won ($74.65 billion) wasn't enough to impress investors in Samsung Electronics, whose shares have fallen about 30 percent from their June 19 peak. On Thursday, the Korean chipmaker estimated third-quarter operating profit at 107.4 trillion won, an increase of 782.5 percent from a year earlier and its fourth consecutive quarter of record earnings. No company, not even tech giants like Apple or Nvidia, has ever surpassed 100 trillion won in quarterly operating profit. Yet the blockbuster results did little to dispel investor skepticism over the sustainability of its earnings growth. On Thursday, Samsung shares closed at 262,000 won, down 2.42 percent from the previous session. Foreign and institutional investors sold a net 348.5 billion won and 647.7 billion won worth of shares, respectively, while retail investors bought a net 959.7 billion won. Foreign investors, in particular, have been net sellers for eight consecutive sessions since Sept. 28. Nick Puckrin, cross-asset analyst and founder of Coin Bureau, said the preliminary results