* Q4 op profit 33.3 bln yen vs 31.2 bln yen analyst view
* FY profit rises 18 pct to 106 bln yen
* Ebates books 51 pct rise in Q4 sales (Adds Ebates contribution, full-year earnings, executive comment)
TOKYO, Feb 12 (Reuters) - Japanese online retailer Rakuten Inc on Thursday said operating profit rose 73 percent in its fourth quarter, boosted by strong growth at recently acquired U.S. discount store Ebates.com.
Japan's largest e-commerce company said profit reached 33.28 billion yen in October-December, versus the 31.2 billion yen average estimate of four analysts polled by Thomson Reuters StarMine.
Rakuten has been on a buying spree in recent years to reduce reliance on its home market, which accounts for around 90 percent of revenue but where growth is constrained by weak consumer spending and a shrinking population.
Chief Executive Officer Hiroshi Mikitani wants to re-invent the company as a one-stop-site for a global audience, along the lines of Amazon.com Inc. It also said last year it would set up a Japanese low-cost airline with Malaysia's AirAsia Bhd.
In October, Rakuten bought San Francisco-based Ebates for $1 billion and immediately saw its new purchase post a 51.3 percent rise in fourth-quarter sales.
"For Rakuten, it (Ebates) is growing to be the second-biggest business model globally after Rakuten Ichiba" e-commerce platform, Mikitani said in an earnings briefing.
Rakuten also reported growth in Viber, a smartphone messaging app it bought a year ago for $900 million. Monthly active users grew 13 percent in the fourth quarter from the third to 236 million, it said.
For the full year, Rakuten said operating profit rose 17.9 percent to 106.4 billion yen. Sales rose 13.7 percent at its domestic e-commerce arm and 17.4 percent in its Internet finance business.
Shares of Rakuten ended 0.4 percent lower ahead of the earnings release, compared with a 1.9 percent gain in the broader market. (Reporting by Teppei Kasai; Editing by Christopher Cushing)