FB reported a net profit of $64m in the last quarter of 2012, compared with $302m a year earlier.
However revenue were up 40% at $1.6bn, largely due to a big jump in advertising revenue.
Shares of Facebook fell by almost 6% ($29) in after-hours trading in NYSE.
FB, made IPO at $38, May, last year. The IPO value had lost 50% by September.