(Reuters) - Amazon.com Inc reported quarterly earnings that beat Wall Street's most bullish expectations after the world's largest Internet retailer brought costs under control, sending its shares almost 10 percent higher.

COMMENTARY:

MARK HARDING, ANALYST, JMP SECURITIES

"Looking at the revenue, it exceeded expectations across the board. Gross margins were actually up on a year over year and sequential basis. Fulfillment costs did increase marginally - certainly less than we were expecting.

"For the quarter, I think they did very well. This was pretty much broad-based across the different segments. I would say the one area of downside that was a little bit weaker was the electronics and general merchandise. Really, the outperformance on the top line was pretty much broad based.

"Revenue guidance was fractionally weak. At the mid-point $12.6 billion that is a little weak but I don't think it's that material. The operating income side is a little bit weaker."

SCOTT TILGHMAN, ANALYST, CARIS & COMPANY:

"This is the second quarter in a row where we have seen that the gross margins have trended better than expected.

It looks like the big swing factor (for the beat) was one, the gross margins came in better than expected, and two, the procurement cost was much lower than expected.

"The one thing that I will look for some clarity on is the guidance. The operating income guidance looks a little bit light for the second quarter, given where their costs and revenues have been trending.

"The biggest concern has been margins. A lot of investors have been looking for the company to demonstrate that it could get leverage on all of these investments it's been making.

"They are very similar to what we saw back in the 2004 to 2006 timeframe when the company was making a lot of investments and margins got squeezed. Then in the years following, margins expanded and revenue accelerated.

"It looks like the company is in that position right now. We might not see quite as much of an acceleration on the revenue, given the size of the company, but it does look like they have the ability to generate the margins."

DAN GEIMAN, ANALYST, MCADAMS, WRIGHT, RAGEN

"Overall, the positives are outweighing the negatives. Certainly the focus at this point is on growth, and they're getting a pass onto the costs, which are definitely eating into earnings.

"The guidance they're providing is a good. There's a ton of long term opportunity out there. Long-term opportunity for them is huge."

KEN SENA, ANALYST, EVERCORE PARTNERS

"The results so far look very good. Revenue beat, margins came in better than expected. We were expecting 15 cents EPS and it came in at 26 cents -- and we were probably the high end of the Street of where the margins were. This was even better than we were expecting.

"You are starting from a very low point: modest improvement on a percentage basis. It looks pretty good. I think the margins have a long way to go, but I think at least to see them moving in the right direction is an encouraging sign."

(Reporting by Jennifer Saba in New York and Sarah McBride and Poornima Gupta in San Francisco)