Greenhill chief executive Scott Bok said in January he needed the US investment banking firm's client base to get "more active" in the M&A stakes after a disappointing set of 2014 results. Three months on, his wish has been granted - by an Israeli drugmaker that has not used Greenhill on a takeover before.

The independent US investment banking firm, which announces its first-quarter results on Thursday, has emerged alongside Barclays as a financial adviser to Israel-based drugmaker Teva Pharmaceutical Industries on its $51.5 billion bid to buy rival Mylan.