The guessing game is well under way: How much will people be prepared to pay for a share in Twitter - $25? $28?
Can the business really be worth $18bn (£11.2bn)? Tonight's sell off of 13 percent of the business will give the company a notional value later in the day.
But these numbers tell you why so many investors are desperate to get their hands on a chunk of the company, even though it has never turned a profit.
Some 500 million tweets are now sent every day - the business is developed far beyond a niche hobby for digital nerds.
Ninety percent of users have a smart phone - and typically they are more affluent than the average consumer, so more attractive to potential advertisers.
Thirty-eight percent of users are between 15-24 with the potential to turn into users through out their lives.
Twitter has a strong presence in economies that are growing strongly like India, Brazil and Indonesia, as well as the US and UK.
As with any technology company being sold to the market there is the risk that hysteria pumps the price way beyond what it is really worth.
But it is easy to see why many investors are excited about the prospect of getting their hands on some of this company.