And that boom has been spectacular. Global M&As were valued at $2.9 trillion in 2005, a 40% increase over 2004 and close to the all-time high recorded in 2000. A new high water mark could well be reached in 2006.

This reflects the quickening pace of corporate restructuring after a period of relative calm in the years after the dotcom boom.

The shake-up is being facilitated by financing conditions that are about as good as they get: strong profitability, buoyant equity markets, still-low interest rates, and the rise and rise of innovative private equity groups.

The M&A machine should continue in overdrive well into next year, and much of this takeover activity will remain international . . . in 2005 the value of cross-border M&As reached an estimated US$827bn, more than a doubling on two years earlier.

Because M&As are corporate Ireland's main route to foreign expansion, this seems to signal that the internationalisation of the Irish firm will continue apace.

Before looking at how fast that has happened in recent years, it's worth asking whether M&As are a good way for Irish firms to globalise.

Observing the almost frenzied global M&A activity over the past two years, one cannot but wonder if the lessons of the past have been unlearnt. The record of success when firms merge or are taken over is far from stellar. Too often, value for the acquiring firm is destroyed, not added to.

This, say some, is because managers and shareholders can have different interests. Too often the former may be unwilling to face the slow grind of organic growth.

Acquisitions are the obvious route for impatient execs anxious to achieve rapid expansion (and lots of limelight). Whether exploitable synergies exist between acquirer and acquired is sometimes not given the prioritisation it deserves.

There are other reasons many M&As fail. Big managerial egos often cannot be contained in a single business and different corporate cultures all too easily clash.

The history of Irish firms' crossborder M&As, with the (not insignificant) exception of the two big banks, has bucked international trends. The firms targeted for takeover appear in most cases to have delivered the synergies identified.

Many attribute this not just to being good at picking winners, but to the manner in which the acquired businesses are brought into the fold.

The 'non-imperial' Irish management style is exemplified by CRH. Though nobody would suggest that the company is anything but a tightly-run ship, its corporate culture appears to value getting buy-in from those it buys over, rather than imposing decisions on managers in the businesses it acquires.

But less alpha male behaviour by Irish managers when they go in to run firms they acquire can't explain everything, as the big banks' poor track record shows. The nature of the industries in which Irish multinationals predominate . . . food, building materials and paper . . . may be another reason for successes to date.

Unlocking value by acquisition is likely to be easier in mature low- and medium-tech industries where change is less rapid and challenges not as multi-dimensional.

Moving from the micro to the macro, how globalised is Irish business in general?

One way to measure the extent of the internationalisation of the Irish firm is by looking at data on foreign direct investment, or FDI (defined as an outflow of capital used to acquire at least a 10% stake in a foreign business).

UN numbers suggest that, as recently as a decade and half ago, Ireland had developing-world levels of outward FDI. The amounts were so small that the Central Statistics Office didn't bother to count them.

This changed in 1998, and we now know a lot more.

In the 1998-2005 period, the amount Irish firms invest directly abroad has gone through two distinct phases.

In the four years, outward direct investment averaged around 5bn a year. This was low by the standards of the time and relative to the size of the Irish economy. It's not hard to see why. The late 1990s saw double-digit economic growth. Making money in such conditions was easier than taking sweets from a baby. Going to the bother of entering a new market when opportunities at home abounded seemed senseless.

But when the home market cooled in the early years of the decade, Irish businesses began to eye foreign opportunities with greater interest.

Since 2002 there has been a step change, and outward FDI has averaged more than 10bn annually.

Cumulatively, foreign assets directly owned by Irish residents abroad grew more than five-fold in just eight years. By the end of 2005, the total stock of Irish FDI abroad stood at 60% of GDP. This is well above the EU 15 average, if still below the top rankers in the Benelux.

And these figures are likely to understate considerably the extent of Irish firms' foreign expansions. Small countries' businesses tend to tap foreign capital markets when investing abroad. This doesn't show up in the FDI numbers. CRH's billioneuro buy last week is likely to end up being one such transaction.

While the successful foreign advance of Irish business has been wonderful for the firms involved, what about the wider economy?

Any really successful multinational will necessarily see its home market sales shrink as a share of its global total. But that need not matter. If businesses keep their headquarter functions in the home base, some of the best-paid and most creative jobs will be retained.

But does that happen? CRH's Dublin-based HQ operations have been hollowed out, with a mere 60 staff running the global show. This works out at less than one HQ staffer for every 1,000 people employed across the world.

There has been much talk about the denationalisation of the firm (the flip side of its internationalisation). With the appointment of Tom Hill as the first ever non-Irish head of CRH's overall American operations, could it be that the firm is readying itself to fly the small home nest?

Dan O'Brien is a senior editor at the Economist Intelligence Unit danobrien@economist. com