$54bn sounds like an awful lot of money to lose in just three months. Is it?

It certainly is.

Indeed, it is the biggest quarterly net loss in history, just nudging ahead of a $51bn loss from tech giant JDS Uniphase last year by a mere $3bn.

$54bn is more than the annual output of a small country such as the Czech Republic or New Zealand.

Such mega-losses seem to be a feature of the post-tech-crash landscape: before the late 1990s, companies that lost in the single-figure billions of dollars in a full year were few and far between.

So is AOL Time Warner in real trouble?

Not as much as it may seem.

The $54bn loss arises entirely from a so-called "write-down".

This is an accountants' technicality involving the revaluation of the company's assets, and therefore of the company's overall value.

In the meantime, AOL Time Warner's performance was more or less unimpaired: its sales were steady, and the firm would have recorded a $2bn profit if the write-down was stripped out.

The book-keeping technicalities are, of course, crucial.

But because they tend to arrive all of a sudden, they make it seem as if a company is swinging dramatically between profit and loss, while the actual day-to-day performance is more or less constant.

Accounting technicalities? Aren't we all supposed to be more worried about those since the collapse of Enron?

Exactly.

The upsurge in write-downs, and other "one-off charges", is at least partly a function of post-Enron nerves.

Stock market regulators are - with good reason - increasingly jumpy about the nasty secrets that companies could be hiding in their balance sheets.

If the authorities are getting tough with auditors, that can only be good news investors, many of whom have been bamboozled by the increasing complexity of corporate accounts.

So it's all good news, then?

Not if you're an AOL Time Warner shareholder.

The write-down may well be a relatively harmless quirk.

But the fact that the firm's assets have been revalued so drastically downwards raises uncomfortable questions about the quality of its management.

In other words, the company is admitting that its assets are worth $54bn less today than it was claiming yesterday.

These sort of embarrassing admissions have been a marked feature of the hi-tech slump.

When media group Time Warner agreed to merge with internet leader AOL two years ago, the combined firms were worth $290bn; now they are worth $85bn.

Somewhere along the way, more than $200bn of investors' money has evaporated - more than four times as much as was allegedly taken from shareholders in the collapse of Enron.

After this write-down, AOL Time Warner hopes to be starting with a relatively clean slate.

But after this, new chief executive Richard Parsons will have a devil of a job to persuade the markets to trust him.