At a mere £3.4bn, AXA's bid for Guardian Royal Exchange (GRE), announced last week, may not be a mega-merger on the scale of some of those recently announced. However, when it comes to complexity there are few to match it.

The deal represents a large jigsaw – the lawyers involved must put many different pieces into place under the demanding deadlines imposed by the City.

The AXA-GRE deal is, in fact, several deals in one. AXA's 71.6% UK subsidiary Sun Life is to acquire the UK and Irish businesses of GRE, but most of the remainder of the GRE overseas companies will be transferred straight over to AXA under a separately negotiated agreement.