Sina Weibo, as expected, has filed with the US Securities and Exchange Commission for IPO to raise up to $500 million. The Weibo Corporation says half of the money raised will be used to repay loans it owes to SINA, its parent company and controlling shareholder.

It claims the monthly active users (MAU) in December 2013 were 129.1 million, a 33% increase year-over-year . 70% of the MAUs accessed Weibo through mobile devices at least once in that month.

Weibo monetization began in 2012. In 2013, Weibo recorded a total of $188.3 million in revenue — an 186% increase year-over-year, with 78.8% from advertising and marketing, 12.2% from gaming and 5.9% from membership subscriptions. 28% of the total were from mobile in 2013. The revenue breakdown in 2012 is almost the same with that in 2013.