New signups on Sina Weibo grinding to a halt?

We heard the bad news yesterday -- Weibo users on Sina, Sohu, NetEase and Tencent have until March 16th to register with their real names and identities, failing which they will no longer be able to post or retweet updates. Sina Weibo, the market leader in the microblogging segment, appears to be already feeling the heat.

Digicha's Bill Bishop observes:

Chinese news reports about the March 16 deadline state that since January 1 Sina has had approximately 3 million real name registrations. If that is accurate then the monthly run rate for new Weibo registrations would appear to have dropped precipitously to 2.5 million or so.

Assuming the 3 million number is correct, I can think of at least three possible reasons for the drop:

1. Sina Weibo has tens of millions of zombie/spam accounts and under real name registration the creation of new junk accounts has ceased;

2. Sina Weibo has already reached the vast majority of potential users and so user growth will slow dramatically as the company shifts to monetizing the existing user base;

3. Potential users are turned off by real name registration and so are avoiding Weibo.

Regardless of the reasons, Sina now needs to start delivering revenue and profit in Weibo. The stock trades at less than half of its 2011 high but is up 50% in a month or so.