Sir Colin Southgate, chief executive of Thorn EMI, yesterday emerged as the company's largest private shareholder, following the exercise of share options just ahead of today's EGM scheduled to approve the demerger of the music and rentals businesses.

Sir Colin generated a profit of pounds 1.2m by exercising options, awarded in 1989 and 1993, and then immediately selling the shares. The proceeds were used to cover the costs of exercising additional options awarded between 1986 and 1988 over 170,000 ordinary shares, which he is keeping.

The dealings, timed to maximise Sir Colin's tax advantages in advance of the demerger, mean he now holds nearly 330,000 shares, worth pounds 5.9m.

Sir Colin said he made the trades in order to "maximise the number of shares I have in the company". He added: "I had to sell shares to finance the exercise. Some people may have a few million up their sleeve, but not Colin Southgate."

The dealings came just days before the demerger is scheduled to take place, on 19 August, after which shares in Thorn and EMI Group will be traded separately. From that date, Sir Colin's share options would no longer have carried the full advantage of tax relief, and he said yesterday: "I would have to be pretty brainless not to do these trades."

Some of the earliest options were awarded in 1986, and would have lapsed if no action had been taken. In addition, the options - granted every year - can only be exercised every three years. Over the past decade, Sir Colin has retained as many shares as possible each time he exercised his options, subject to covering costs.

Simon Duffy, the finance director, has also exercised options, borrowing money to hold a total of 154,750 shares.

Shareholders of Thorn EMI will meet today at an extraordinary meeting to approve the demerger. The company has been the target of speculation that a suitor would appear to break it up, although analysts now expect no action until after the demerger goes through.

The key attraction is the EMI music business, one of the world's largest, which will become the only top company in its sector not already owned by a big media conglomerate.

Potential buyers include Disney, Rupert Murdoch's News Corporation and Seagram, the Canadian company that last year bought MCA, the Hollywood studio.