Alibaba's sales for Singles' Day, China's equivalent of Cyber Monday, passed the $9 billion mark late Tuesday, topping last year's record of around $5.9 billion.

The total, measured as gross merchandise volume, was announced via Alibaba's Alizila.com Twitter account. It said that 42.6 percent of sales were generated via mobile.

Singles' Day—so named because the date Nov. 11 has four singles (11/11)—was started as an in-joke between university students, but has morphed into China's equivalent of Cyber Monday. Spurred by Alibaba and its network of online retailers, the day has grown from $7 million in sales in 2009 to over $5.7 billion last year for Jack Ma's company.

This year, Alibaba's sales are expected to be about 50 billion yuan ($8.17 billion), a 40 percent increase from last year, according to Ben Cavender, principal at China Market Research Group.

That compares with Alibaba's total revenue of 16.8 billion yuan for the September quarter alone, while GMV for the China retail marketplace was at 556 billion yuan in the quarter.

However, in its first earnings statement since its record IPO, Alibaba Group reported results that met analyst expectations but showed the company's costs are growing.

According to technology expert, Mohanbir Sawhney, “As it seeks to expand beyond its roots as an online marketplace, Alibaba will face further challenges to keep its profit margins attractive.”