It's hard to figure exactly what chairman Paul Coulson is up to at glass bottler Ardagh. Mr Coulson, who was the main architect of Ardagh's audacious £283 million (€359 million) takeover of Rockware last year, has now increased Yeoman's stake in the glass bottler after buying 1.35 million shares in recent weeks - taking Yeoman's stake to just over 19 per cent.

Ardagh might have paid £283 million in equity and various types of debt for Rockware, but, judging by the reaction in the market since then, the acquisition - which quadrupled Ardagh's size in terms of sales - might as well not have taken place.

Despite being the biggest glassmaker in Britain and Ireland, and a serious player in European terms, Ardagh's share price has gone the same way as most other mid-caps - through the floor, from €2.60 to a low of €1.20 earlier this year.

Mr Coulson and his partners in Mercury Asset Management - a long-time big and supportive shareholder - could be forgiven for wondering what exactly they had done wrong.

The buy-back of 2.5 million shares at €1.61 each last month has gone a little way towards tightening up liquidity and supporting the share price, but clearly Mr Coulson believes that Ardagh shares are still a bargain and thus the decision to increase Yeoman's stake from 15.1 per cent to 19.1 per cent.

Only two years ago, Yeoman's stake was just 8 per cent.

That means that Mr Coulson and Mercury - which did not sell into the buy-back - between them now control almost 52 per cent of Ardagh shares, leading to the obvious question: are Yeoman and Mercury planning to buy out the remaining shareholders and take Ardagh private? The indications are that they are - the only question in the market is when.

If Coulson and Mercury do decide to buy out the remaining shareholders, they should find a receptive audience. Virtually all the major institutional shareholders sold stock in the buyback at €1.61 a share. Bank of Ireland Asset Managers reduced its stake in the buy-back by over a million shares, Friends First sold almost 750,000 shares while Davy Nominees sold almost 350,000.

The only institutional shareholder with a disclosable stake that did not sell into the buy-back was the ESB Pension Fund, whose stake has as a result gone up from 3.1 per cent to 3.3 per cent. This suggests that if there is an offer to take Ardagh private at any decent premium to the current price, then there will be no shortage of takers.

Financing such a deal would be a complicated piece of financial engineering - on top of the complicated takeover of Rockware. But the Ardagh board has plenty of financial know-how when it comes to putting together buyout packages, with accountant Bernard Somers and stockbrokers Brendan Dowling and Ray French all on hand to lend some advice.