Alibaba shares tank after margins decline, market value dips $30 billion

Alibaba's Chief Financial Officer Maggie Wu said on a conference call that investors shouldn't equate lower margins with lower profits, as the overall business is growing

Alibaba Group Holding Ltd shares fell the most in 18 months and cut its market valuation by about $30 billion after investments in brick-and-mortar assets and digital media squeezed profit margins in the December quarter.

The Chinese e-commerce giant reported revenue that topped analyst estimates and raised its growth forecast for the 12 months ending in March to 55 to 56 percent. But operating margin shrank to 31 percent in the last quarter from 39 percent a year earlier. Shares fell 5.9 percent in New York trading, the sharpest decline since June 2016.

Alibaba will also buy 33 percent of Ant Financial,