The $8.6 billion sale of Irish biotechnology company Elan to US pharmaceutical Perrigo, announced this summer, marked a bittersweet moment for Michael Tory, a founder of advisory firm Ondra Partners.

The deal, which trumped an earlier bid by Royalty Pharma, represented one of the biggest deals yet for the advisory firm Tory co-founded with Benoit D'Angelin and Michael Baldock. But there was reason to pause for thought: a little less than five years earlier, in the wake of the collapse of Lehman Brothers, Elan had been Ondra's first paying client.