Like quite a lot of people I became a Halifax shareholder earlier this month - a status automatically conferred by the possession of a savings account. And like quite a lot of people I had been lured by the rising scent of a windfall into the unfamiliar terrain of the financial pages, where I had been informed by almost every authority that the canny thing to do was to make sure that I got the paperwork into my own hands. So, feeling as sly as George Soros on a bad day for the pound, I ticked the relevant boxes and sent off my envelope. But what all those journalists had failed to inform me was that I was also entering a world in which nothing quite made sense, in which my notional prosperity would rise and fall with a baffling choppiness. The Halifax might have added some money to my life but it had also added a new plot in which anxiety could flourish.

Truth to tell, though, it wasn't really the Halifax shares that taught me this because I did have some previous experience in the shareholding game. When the rather anti-climactic Halifax certificate arrived (Why no steelpoint engraving of head office in 1863? Why no scarlet wax seal?) it joined one other piece of paperwork in my anorexic portfolio, a very modest investment in a computer games company called Eidos (Can't recommend it too highly. Get in now while the going's good. Trust me). I had bought this on the recommendation of a stockbroker friend, something like the third or fourth tip he had casually passed on between courses at Sunday lunch though I hadn't acted on any of his previous advice, partly because I had no idea of how you went about buying shares and partly because I wasn't sure exactly what insider dealing consisted of.

This moral uncertainty was just as groundless as the disquiet that afflicts me when I blamelessly pass through the Green channel in Customs, but I couldn't quite shake the apprehension that my request for 300 shares in Blenkinsop Plc (a number that struck me as recklessly large) might ring alarm bells in the City. In some secret headquarters a crack team of market regulators would be scrambled; I would be interrogated as to exactly how much I knew about compressor manifold technology and what grounds I had for believing that an investment in this sector would pay off just now. My friend might even be stripped of his red braces and forced to take up productive employment. In other words I had a bad case of what the Germans call Schwellenangst - literally, threshold-fear, the terror of entering unfamiliar spaces.

But the advice certainly seemed to be sound (I followed his tips like a non-betting punter watches the Derby, fantasising that I had re-mortgaged the house and put it all on the lead horse) and when he gave another recommendation I decided to follow through. Buying the shares was relatively easy (after an indignant and then embarrassed telephone call had established that the price quoted in the newspaper was a mid-point between the buying and selling price and that I had not, as I instantly assumed, been fleeced by wolfish dealers on the lookout for lambs). A few days later I swapped a chunk of my deposit account for a drab piece of paper recording my ownership of a vanishingly small section of the computer games industry. Then I waited for overnight enrichment. You hardly need me to tell you what happened next. Eidos shares seemed to have taken it upon themselves to demonstrate the truth of that warning about prices going down as well as up. They demonstrated it with what seemed to me quite unnecessary zeal. While other companies bobbed gently up and down, their share prices rarely straying more than a few pence from what they had been the day before, mine reared and bucked like a powerboat in high seas. Either the market knew something I didn't or they didn't know anything at all. Neither was a comforting thought and, unfortunately, at least in my brief association, the trend was downwards (my paper loss at present, not counting fees, is a little over pounds 150 - a fact my friend is reminded of with heavy sarcasm every time we meet).

Still, there are distractions. Owning shares adjusts one's perceptions in a rather odd way, a fact that the Halifax dispersal has confirmed. You find yourself sensitised to areas of the world that previously might not have existed. When I spotted Lara Croft (pixillated heroine of one of Eidos's best-selling games) on the cover of The Face my spirits lifted, only to be brought down to earth again by the revelation that U2 (who have adopted Lara Croft as a kind of tour mascot) were having trouble selling concert tickets. How was I to read these distant eddies of good and bad fortune? More to the point how was I to read the share prices? The P/E ratio, patiently explained to me on several occasions, turned out to be one of those scraps of knowledge for which there is no effective synaptic glue (along with the offside rule and braking distances in wet conditions). Should it be high or low? And what is considered high anyway? What's more even the benison of the Halifax wasn't without its fretful aspects. Strictly speaking, of course, I am better off than I was - but given that the share price has fallen from the overexcited high at which it launched, it's difficult to prevent the calculation turning into one of loss. Shares have opened up for me an entirely new worry-seam, and the yield looks as if it will be impressive for years to come. There is an obvious solution - liquidate my holdings with a prescience even Jimmy Goldsmith might admire. But I think I'll just wait to see what the markets do tomorrow