South Korea's POSCO (005490.KS), the world's No.4 steelmaker, warned on Thursday of lower 2009 steel output and sales due to slumping demand as it reported sharply lower-than-expected and barely changed quarterly profit.

October-December net profit at POSCO, which ranks behind ArcelorMittal (ISPA.AS: Quote), Nippon Steel (5401.T) and JFE (5411.T), edged up 1 percent to 721 billion won ($527.3 million) from a year ago but fell 41 percent from July-September quarter.

The final quarter result was sharply below a forecast for 1.15 trillion won from 10 analysts polled by Reuters Estimates.

Weaker demand for everything from autos to home appliances due to a deepening global economic recession will crimp earnings at steel majors this year, in a sharp reversal from the sector's record profits logged last year.

Shares in POSCO, South Korea's second-largest listed company, dropped 14 percent in the fourth quarter, outperforming a 22 percent drop in the broader market .KS11. ($1=1367.4 Won) (Reporting by Miyoung Kim; Editing by Keiron Henderson)

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