IG Group and ETX Capital already allow (greymarket) trading of Twitter shares.

It seems as if those who bought in (very) early to Twitter are already ahead…. Social microblogging site Twitter has finally made final its IPO prospectus, which includes its plans to value the company at about $12.8 billion. As we wrote earlier, several UK spreadbetting firms, led by IG Group and ETX Capital, very quickly launched greymarket trading in Twitter stock after Twitter announced its plans to go public in early September, but before it had publicly disclosed its detailed financials.

The Twitter trading at IG and ETX is based on Twitter’s overall valuation. When first launched, traders were betting on a $10.5-$11.5 billion valuation range for Twitter. That is sure to pop today, after Twitter indicated it is aiming at a $12.8 billion valuation.

And for those of you who were wondering — no, Twitter is not going to go with the stock symbol TWIT! Twitter and its underwriters have chosen a much more neutral stock symbol TWTR. Interestingly, Twitter did NOT indicate on which market it will list, leaving both the NYSE and NASDAQ still fighting it out to land the year’s most prestigious new listing.

Early word we’ve heard is that Twitter greymarket trading has indeed been very light so far at both IG and ETX, although it has been a very interesting marketing tool as both firms increasingly target the ‘retail’ crowd — IG in particular is in the midst of a major marketing campaign boosting its image as a Forex broker, including IG’s new MT4 capabilities and its new IG.com website. However, with Twitter’s filing and numbers out in the public domain now, it is expected that Twitter greymarket trading will increase leading up to the actual IPO.

To see the complete Twitter IPO prospectus (technically an S-1 filing with the SEC) click here.

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