SanDisk (SNDK) reported a better-than-expected rise in second-quarter profit, as its growing focus on high-end solid-state drives helped offset volatile prices for memory chips.

However, the company's shares fell 6.6 percent in extended trading. The stock has risen about 42 percent and has been trading at life-high levels since the company last reported results in April.

SanDisk has beaten analysts' estimates handily for at least the past eight quarters, but the 1.5 percent margin by which the company's profit topped estimates the quarter ended June 29 was much lower than the previous eight.

"Investors were expecting too much. Last couple of quarters the company had some blowout numbers so expectations had gone up," said Betsy Van Hees, an analyst at Wedbush Securities."

"We haven't got the guidance yet, which is going to come out in the conference call, ... and the stock is likely to reverse after those numbers," she said.

SanDisk is increasingly using its chips in solid-state drives, or SSDs, which it sells directly – a strategy that offers higher margins than its traditional business of selling memory chips for smartphones and cameras.

Revenue from SSDs comprised about 29 percent of the total revenue in the quarter, up from 16 percent a year earlier.

The company which counts Facebook Inc and Apple Inc among its customers, said revenue rose 11 percent to $1.63 billion from $1.48 billion.

Net income rose to $273.9 million, or $1.14 per share, from $261.8 million, or $1.06 per share, a year earlier.

Excluding one time items, SanDisk earned $1.41 per share. Analysts had expected a profit of $1.39 per share on revenue of $1.60 billion, according to Thomson Reuters I/B/E/S.

Shares of the company closed at a life-high of $107.83 on Nasdaq on Wednesday.

(Reporting By Lehar Maan in Bangalore; Editing by Savio D'Souza)