The completion of Vodafone's Verizon Wireless sale is set to prompt the largest capital return in corporate history and will have a drastic impact on UK trading volumes over the next few weeks, according to analysts at Bank of America Merrill Lynch.As part of the $130bn deal to dispose of Vodafone's 45% stake in its joint venture with Verizon, 71% of the proceeds - $23.9bn in cash and $60.2bn in Verizon shares - will be distributed back to Vodafone shareholders when the deal completes on Friday.With a third of these shareholders based in the UK, BofA said that market volumes will be significantly affected "by the re-investment of cash proceeds, the scale of flowback in Verizon shares (both automatic and discretionary), and the rebalancing of index weightings (particularly the FTSE 100 and FTSE 250)".The bank explained: "Though the scale and timing of market impact is difficult to forecast, we expect market volumes to be significantly affected on Friday February 21st, Monday February 24th and Tuesday February 25th, with further impact likely over the coming weeks."BofA added that an options expiry on Friday and a FTSE and MSCI rebalance on Monday are also expected to impact the level and distribution of volumes throughout the day.BC