Twitter is hoping to raise up to a billion dollars from issuing stock to the public for the first time. But it’s revealed it has never made a profit despite huge growth.

To date, Twitter’s finances have been kept under wraps. It didn’t even publicly reveal any profit & loss or revenue figures when it first filed the Initial Public Offering documents, taking advantage of a rule that allows “smaller” businesses to delay that publication until it starts running presentations to potential investors, which is now happening.

The documents show Twitter has lost money every year, with current total losses of $419 million. Those would be more than wiped out if the flotation goes to plan: the stock price will likely value Twitter at $10 billion if not more, with the aim of pulling in at least $1 billion from the stock sold to the public.

The company is certainly growing quickly: between January and June this year it pulled in $254 million, compared with $122 million in the same period last year. However, it’s losses for the six months also grew, from $49.1 million to $69.3 million.

That compares poorly with Facebook, which listed rising profits for the three years leading up to its own flotation, and revenues around 10 times that of Twitter.

The Twitter filing also shows it gets 87 percent of its revenue from selling advertising with the rest from licensing deals, for example to allow large companies better access to its data.

It could be worrying news for users as boosting ad revenue seems to be the only way Twitter can break into profit. The company notes its had success experimenting with a wider range of ads, some at lower prices. It also points out it gets the majority of its ad revenue from mobile devices, which is a growing market.

But it still seems likely that ads will have to get more frequent and more prominent if Twitter is to boost its finances, something that risks deterring users. Reuters estimates that between April and June this year Twitter pulled in 64 cents of revenue per user, compared with $1.60 for Facebook.