A fine old row is brewing over the subject of company registrars and shareholder nominee accounts. Don't yawn - something good may come of this, and something which is arguably bad may be changed. And sooner or later it is likely to affect all of us.

The argument has been taken to the Office of Fair Trading by APCIMS, the Association of Private Client Investment Managers and Stockbrokers, who are upset by what they claim are ''various anti-competitive practices of certain plcs and their corporate registrars''.

The immediate problem concerns the millions of new shareholders being created as building societies join the stock market, handing round windfalls on the way. Six, including Abbey National, the trail blazer, have travelled or are travelling this route, and this week also saw the Norwich Union insurance group abandon mutuality, to the delight of a host of policy-holders who suddenly found themselves shareholders. Others, including the Nationwide building society and insurer National Provident Institution in particular, are under pressure to join them.

The worry is over ''the actual and potential effect on competition arising in the market for the provision of share nominee services'' now that corporate registrars are in this market. As companies have only one such registrar, it has a monopoly for that company's registration services ''and this is increasingly being used unfairly as a springboard into neighbouring markets, particularly those for the provision of share nominee services''.

What is happening - and what brokers think will happen on an increasing scale, as one of the big registrar companies is said to be trying to persuade more companies to use it for nominee services - is that more and more shareholders will be effectively tied to that registrar's nominee.

The scale is huge, when you consider that demutualisation windfalls are creating some 18 million new shareholders, not all of whom will sell at the first opportunity, and also that existing shareholders will be encouraged more and more to go into a nominee - whether corporate or broker. There the shares will be held electronically and more easily traded through the Crest settlement system than if a paper certificate has to be dealt with. Brokers don't like it because corporate nominee shareholders will be much more difficult for them to get at and deal for.

The inactive shareholder, perhaps getting a company perk which he likes, should be comfortable enough in a corporate nominee. More and more companies are following the advice which Justin Urquhart Stewart, of Barclays Stockbrokers, has been hammering for some time, and seeing their shareholders as potential customers and supporters. They ensure those in their nominee get reports, perks, and special offers, which traditional broker nominees have not always been keen to pass on.

As Mr Urquhart Stewart says: ''There has to be a change of attitude. Brokers have to have more user-friendly nominees. There is a new market developing.''

The APCIMS argument accepts that holding shares in electronic form in a nominee is a sensible thing nowadays, allowing shares to be bought and sold more cheaply. But it wants equal treatment and objects to nominees who make it harder or dearer for the shareholder to sell through an independent broker.

Holding shares electronically in nominees rather than via paper certificates is likely to become more fashionable. If the current row loosens things up, making corporate nominees more flexible and broker nominees more keen on passing on perks and information (currently you may not get an annual report) so much the better.

Then, of course, there should be more pressure on PEP managers to do the same and also to make it easier for investors to switch their PEP accounts. Currently, if you have more than one year's PEP allowance with a manager you may have to switch all or nothing if you want to test out a new manager. Ideally, you should be able to switch one year's allowance for a trial, leaving the rest with the existing manager. Fairness and flexibility should be the keys.

SHAREHOLDING