Assuming that $1000 dollars is a significant percentage increase I don't really know how else you'd make such a substantial gain in one day when the markets have tanked.
Spreadbets maybe? CFD's? 
Then again I don't work in finance. 
What do you do Dumah? Are you worried at all?
Investment managers earn their salaries by holding a diverse range of assets with different forms of risk. A typical fund will contain assets (shares & derivatives) backed by gold, shares (over loads of different industries), bonds (corporate & government), commodities, property, and all sorts of other stuff. Having a diverse mix means that market events will have an effect, but hopefully not wipe out the whole fund. Hypothetically, imagine the fund was 100% shares in Lehman - you'd have nothing today, then imagine it was 100% gold - youd have made an annual equivelent of 20% gain between Friday and Monday. The thing a good fund manager does is to play different assets off, minimise the risk & get a decent return.
What I was trying to point out is that this event has had a massive affect on most asset classes and it's fair to say that the vast majority of well managed funds have fallen in value. For the fund manager to make a sudden gain means he was either exceptionally lucky that the assets he manages have gone against the trend or that he's a massive gambler and has bet a huge amount on Lehman going bust. For one financial transaction to prop up the fall in the rest of his fund it would have to be pretty massive. Remember, if Barclays bailed them out over the weekend, he'd have probably sent his own fund bust as the gamble failed - not a good thing for man who is paid to be a "safe pair of hands" to do.
Am I worried - a little because we are a year in now and big things are still happening. There's no point worrying though as you cant change things so worrying only hurts yourself.
No matter what the state of the economy, you have to remember that you are on a cycle. If it's bad now, then it'll get better eventually. Then it'll go to shit again in a few more years.
Just make sure though, that if the worst comes to the worst that you have a shotgun and enough tinned food to see out the winter!
Maybe my previous balance was higher than I remember
That might well be probable...
