(Reuters) - Shares in Samsung Electronics, South Korea's most valuable firm, fell 3 percent in early trade on Monday, extending falls into a second day as investors took profits following a one-month surge.

Samsung shares soared 23 percent from its most recent trough registered on July 12, outpacing gains in the main board by nearly three-fold.

(Reporting by Joonhee Yu; Editing by Richard Pullin)