By Gerry Shih SAN FRANCISCO (Reuters) – Twitter Inc reported its slowest pace of user growth during the fourth quarter, dimming hopes that the social media phenomenon can sustain its torrid pace of expansion and wiping out more than 10 percent of its value on Wednesday. Twitter, which held a highly-anticipated initial public offering in November at $26 a share, has divided investor opinion in the months since, as shares raced to more than $66 ahead of Wednesdays results, despite an absence of news. Twitters valuation was predicated in part on the belief it could expand its appeal and eventually grow to a scale close to Facebooks, which has five times as many users. Twitter averaged 241 million monthly users in the December quarter, up just 3.8 percent from the previous three months – the lowest rate of quarter-on-quarter since Twitter began disclosing user figures.