History has not judged megamergers kindly. Of the 10 biggest, five took place shortly before the bursting of the dotcom bubble, including Vodafone ’s notorious acquisition of Mannesmann. Another three were in the late stages of the pre-Lehman boom, notably the purchase of ABN Amro by a Royal Bank of Scotland -led consortium — perhaps the dumbest deal of all time. Shell ’s £55bn deal for BG Group on Wednesday ranks as the ninth-biggest in that list, according to Dealogic. So, should shareholders be concerned that the return of the titanic takeover means equities are toppy? Start with the past. It is no coincidence that the really big deals happen when the market is frothy. The logic is the same as that behind the world’s tallest towers : investors and lenders are willing to countenance such financial nonsense as the Burj Khalifa, or London’s Shard, or AOL – Time […]