Denis O’Brien has offloaded a long list of assets in the last 18 months, leading to inevitable speculation as to why he is selling so much, and why now.

He only turns 58 next month, so O’Brien is far from retirement age. He doesn’t seem the retiring type, anyway. It is difficult to imagine Ireland’s most powerful businessman selling up and slowing down.

His latest asset sale, offloading the Canada House office block for €85 million, will turn him an estimated profit of more than €30 million. In December, he made a profit of probably more than €250 million when he sold filling station chain Topaz to Couche Tard.

O’Brien also picked up an estimated €84 million last year when he sold his stake in Australian media company, APN. He also offloaded BB’s the Coffee and Muffins chain for €10 million.

He considered selling his Quina Do Lago golf resort in Portugal for in excess of €220 million, before pulling the sale when offers didn’t meet his expectations.

He has also sold out of Saon recruitment group, and later also flipped the ChinaHR business he had retained. In late 2014 he also sold his 80 per cent stake in Aergo Capital, an aviation leasing company.

The sum total he has raised is difficult to ascertain, but it could well be in the region of €500 million. That is roughly equivalent to the amount he spent and mostly lost on Independent News and Media shares before its restructuring.

Last autumn, O’Brien also sought to float Digicel on the stock exchange, which would have given him a ready-made exit strategy from the business that is the source of much of his paper wealth.

The flotation was later yanked because O’Brien’s valuation of Digicel did not match that of his would-be investors.

Will he really have another bite at floating Digicel in 2016? It will be difficult. Market conditions are barely any calmer now than when he abandoned his first attempt. And if he didn’t like the price on offer then, he would be unlikely to fare any better now, given the competitive headwinds facing the mobile and telecoms company in the Carribean.

Actavo, his infrastructure business previously known as Siteserv, is growing fast abroad, but would appear profitable enough to finance its own expansion without resorting to its majority shareholder for capital.

Perhaps O’Brien doesn’t have any particular reason at all for raising capital right now, and simply believes the time is right to cash in on some of his assets. Or perhaps he plans to deploy the cash elsewhere in his business empire.

Either way, it is difficult to escape the thought that O’Brien is up to something.