Samsung Electronics <005930.KS>, the world's top maker of memory chips and televisions, estimated on Friday its July-September operating profit would fall 14 percent from a year ago, as persistent declines in semiconductor and flat screen prices outweigh a strong profit recovery in its handset business.

The South Korean firm estimated its quarterly operating profit at 4.20 trillion won ($3.5 billion), compared with a consensus forecast of 3.4 trillion won by analysts surveyed by Thomson Reuters I/B/E/S. That would be a 13.6 percent decline from a year ago but up 12 percent from the preceding quarter.

Samsung, the world's biggest technology firm by revenue, estimated third-quarter sales at 41 trillion won. The company will provide detailed earnings later this month.

Shares in Samsung, Asia's most valuable technology firm with a market value of around $118 billion, have dropped 5 percent over the past three months, outperforming a 21 percent fall in the wider market <.KS11>. ($1 = 1191.000 Korean Won)

(Reporting by Miyoung Kim; Editing by Matt Driskill and Jonathan Hopfner)

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