Even in these grim times, deal makers have descended into silliness.

Perhaps it is end-of-the-year exhaustion as we sputter toward the finish of a five-year market rally, but normally sober-minded business executives seem to have thrown over sound decision making for flights of fancy.

The prime example of silly deal-making has to be Pfizer’s $152 billion tie-up with Allergan. Pfizer, the largest drug maker in the United States, is the acquirer in all but name. Its chief executive remains at the top, and Allergan’s stockholders receive a premium.

But the deal is structured to give it the tax benefit that would come with an inversion. Technically, Allergan will be the acquirer and in the transaction Pfizer, based in New York, will relocate its place of organization — and tax domicile — to Ireland.

Pfizer wants to acquire Allergan not to build a better business by bringing together the makers of Botox and Viagra, but because the move will lower its taxes.