Twitter Inc (NYSE:TWTR) shares are now worth nearly triple what they were at their initial public offering last month, and their price just keeps going up. Shares surged nearly 5% today, hitting yet another new high, and volume went through the roof. The company’s daily average stock volume is a little over 15.2 million shares, but today, more than 61 million shares of Twitter have traded (hat tip @optionmonster). And the trading day isn’t over yet.

Twitter share volume soars

By the time you read this, that 61 million number could be greatly under what you see if you check because it looks like shares of Twitter just keep changing hands over and over. Just check out Twitter Inc (NYSE:TWTR)’s on Google Finance and hit refresh a few times if the trading day is still open. This number is still popping.

According to CNBC, Twitter’s $40 billion market capitalization makes it more valuable than much of the S&P 500. The Wall Street Journal reports that Twitter will be one of the top 100 companies within the index. It is even outpacing other social online companies, including Facebook Inc (NASDAQ:FB), Yelp Inc (NYSE:YELP) and LinkedIn Corp (NYSE:LNKD). None of them achieved the same extraordinary gains Twitter has during their first couple of months on their respective stock exchanges.

Matt Drudge sees “horrific” crash ahead for Twitter

Because of the dramatic exuberance over Twitter Inc (NYSE:TWTR), Matt Drudge of the Drudge Report tweeted that he sees a major crash ahead for the micro-blogging site’s stock. According to Drudge, the upcoming crash of Twitter shares will be “horrific.” He questions how company like Twitter, which has yet to turn a profit, can hit a stock value of $41 billion.

Business Insider‘s Jay Yaro suggests some ideas about why Twitter shares have performed so well so far this year. He notes that so far this month, the site’s shares have risen approximately 80%. Just in the past week, they have risen 33%, and he says “no one really knows why.”

Why might Twitter be doing so well today?

Yarow suggests some possibilities, including a short squeeze, major funds buying Twitter Inc (NYSE:TWTR) just so it’s in their portfolios, investors “suddenly” seeing mobile ads as being “huge,” or “something else.” Today in particular, Twitter shares may be affected by a report which indicates dramatic increases in the company’s advertising share. The number of advertisers using Sponsored Tweets rose to 52% this year, according to a report from IZEA.