Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of SINA Corp. (NASDAQ:SINA) rose more than 10% early Monday, then settled to close up around 6.6% in its first trading day since Weibo filed paperwork with the SEC for an initial public offering.

So what: As 77% owner of the Chinese microblogging site, SINA stands to gain the most from Weibo's offering. Meanwhile, individuals and 18% stakeholder Alibaba make up the balance, though Alibaba will almost certainly exercise its option to increase its stake to 30% before the IPO.

This also confirms a Wall Street Journal report almost three weeks ago, which came on the heels of SINA's fourth quarter report. Shares plunged following that report, in which SINA revealed Weibo's December average daily active users increased just 4.2% from September to 61.4 million, or a notable deceleration from the previous quarter's 11.2% gain.

Now what: Also keep in mind $500 million isn't a final number, but rather a placeholder. To be sure, SINA shares spiked on March 6 following reports Weibo's potential IPO could raise at least $1 billion for its owners.

Even so, considering SINA management has pointed toward Weibo as the very reason its last two quarters have exceeded expectations, I'm not particularly anxious to dive into SINA just yet. Rather, I'm perfectly happy letting the dust settle and seeing where the company heads from here before I make any decisions from a long-term investing standpoint.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.