At the beginning of June, on a whim of my daughter's head teacher I started a three week fantasy share portfolio among her class.
It was based purely on FTSE 100 companies, but ended up reflecting what is going on round the world.
Had real money been involved I would be facing court actions from 15 understandably distraught parents.
If the children learned anything, they learned the truth behind that trite caveat "the value of your investment can go down as well as up".
In fact I think they came away imagining that that was all shares ever did.
One poor girl bought $2000 (£1,000) worth of UK housing company Barratt Developments and saw her money reduced by almost 60% in three short weeks.
Best performing Global 30 stocks
The canniest of them cottoned on to what was happening around week two, and switched into resource stocks - Rio Tinto, BP, BHP Billiton and BG.
By the end of the month he was beginning to recover some of his losses, but only just.
The miners and oil companies have not had it their own way, and even as commodity prices edge ever higher, there seems to a law of diminishing returns in play.
BP is down 4% although that is partly because it has been forced to contend with a bitter wrangle for control of its Russian joint venture TNK-BP.
Certainly Rio Tinto sealed an iron ore deal with the Chinese that almost doubled prices and ensured that global costs would push ever higher for the next year.
But Rio Tinto shares are down 9.8% in the last month.
Meanwhile Anglo American has been booted out of the Global 30 and replaced by Arcelor Mittal, now the world's biggest steel company. But even its shares are down 6.6%.
Symbian plan
Individual good-news stories have had little redemptive effect.
Worst performing Global 30 stocks
Nokia shares are down 16.9% in the month when it bought full control of Symbian, which makes the software for its phones.
More importantly, it's setting up the Symbian Foundation to give away the software.
It'll lose millions in software sales but it will make it easy to develop applications for the new system, which will boost market share for Symbian handsets.
This is all bad news for Google, Microsoft and Research in Motion who are faced with the problem that their main rival for mobile software is giving it away free of charge.
"The last 12 months has seen the nature of the mobile industry and its software alter as new companies entered the mobile space with their equipment using Linux open-source software," explains Stephen Pope, chief global market strategist, Cantor Fitzgerald Europe.
"The next stage in mobile communications will determine how phones evolve and also how quick and user friendly the mobile net will become."
Impact spreads
There are no housing stocks in the Global 30, but evidence of the collapse of the US housing market can be seen right through the index.
Global 30 mid-year reshuffle - coming in
This was the month that the index got reshuffled and it's a sign of the times that Bank of America, which replaces Citigroup was seen fit to take its place even as its share price fell by 29%.
It was still the best of the financial bunch.
Citigroup's share price has fallen by almost 70% in the last year, ravaged by its exposure to sub-prime mortgage financial instruments.
In the last week of the month those glib phrases about lines being drawn under the sub-prime crisis melted away like ice cream on a beach, as speculation grew that more write downs in the finance sector are on the way.
Some $400bn (£200bn) is the total so far, and there may be more to come.
Running out
And as falling house prices (specifically in the US, UK, Ireland and Spain) make people feel poorer, food and fuel prices are actually making them poorer.
Global 30 mid-year reshuffle - going out
Toyota's shares fell 7.7%: it may produce fuel efficient cars, but new cars are costs that people are finding hard to afford.
Despite the much vaunted efficiency of its factories it has failed to switch fast enough from sports utility vehicles, or SUVs, and trucks to fuel efficient cars.
Toyota is perilously close to running out of specialist batteries for its hybrid cars - sales in the US fell by one fifth last year.
No defence
Procter and Gamble whose drinks-to-detergent business should be a bulwark in times of trouble has seen its shares fall 8.8% as costs ratcheted up.
WalMart has been discounting its goods heavily over the last few months, and its shares have outperformed the S&P 500 by some 30% this year.
Even so, the relentless bearish sentiment across the markets sent them down 3.4% through June.
It's a similar picture in Australia where Woolworths, which joined the Global 30 in June, is hanging on to its predictions of 21-25% profit growth this year, even though the last month saw 15.7% wiped off its share price.
Tesco in the UK is reducing the price of 3,000 items by up to 50%. Its shares are down 10.8%.
Discounting failed to rouse AT&T's shares. It's subsidising handset costs and commissions in order to win market share, but analysts are complaining it will not help the bottom line for two years - or more. The shares fell 16.2% in June.
Alone among the Global 30, one miner, BHP Billiton, and two classic utility defensive stocks, Tokyo Electric and Exelon, have made gains.
There seem to be precious few places to hide for international equity investors, let alone schoolchildren.
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