Sina Corp., which operates a popular Chinese Web portal, said Wednesday that its first-quarter profit fell 38 percent as higher marketing and engineering expenses for its Weibo microblog service and video initiatives overshadowed revenue growth.

Sina said it earned $15 million, or 23 cents per share, for January through March, compared with $24.4 million, or 37 cents per share, in the first quarter of 2010.

Excluding one-time items, the company earned 25 cents per share, a penny less than analysts expected on average, according to FactSet.

Revenue rose 18 percent to $100.2 million, slightly more than the $98.4 million analysts expected.

Sina said advertising revenue climbed 33 percent to $72.3 million, while non-advertising revenue — which is composed mainly of Sina's mobile services — fell 9 percent to $27.9 million.

The company said revenue from mobile value-added services, which can include things like ringtone downloads, fell 13 percent to $21.3 million due mainly to rules implemented by China Mobile in late 2009 and early 2010.

Costs rose too, climbing 25 percent to $41.8 million.

Sina shares rose $3.26, or 3.7 percent, to $123.06 in after-hours trading, having finished regular trading down 29 cents at $119.80.