Inc quarterly earnings fell far short of Wall Street estimates as operating expenses surged, sending its shares down 14 percent.

Net income in Amazon's second quarter rose 45 percent to $207 million, or 45 cents per share, from $142 million, or 32 cents per share, a year earlier.

Analysts, on average, had been expecting earnings of 54 cents per share, according to Thomson Reuters I/B/E/S.

Revenue rose 41 percent to $6.57 billion, just above the $6.54 billion expected by Wall Street. Total operating expense rose 40 percent to $6.3 billion.

Amazon forecast operating income in its third quarter to range between $210 million and $310 million -- representing a potential drop of 16 percent to a gain of 24 percent -- on sales of $6.9 billion to $7.63 billion.

The largest global online retailer, fueled by buzz from its Kindle e-reader, had posted blow-out results in its fourth and first quarters, but investors had feared the momentum would stall this spring.

Amazon recently lowered the price of its Kindle in light of market competition from Apple's iPad and a cheaper Nook device from Barnes & Noble, and has begun to sell the device in Target stores.

(Reporting by Alexandria Sage; Editing by Gary Hill)