BHP Group is likely to sweeten its $43 billion takeover offer for Anglo American for a second time and possibly add cash, investors in both companies said on Tuesday, after the London-headquartered target rejected a higher bid.

BHP made an all-share offer last month, which Anglo American refused the following day, saying it “significantly undervalues” the company. On Monday, BHP said it revised its offer up on May 7 to give Anglo shareholders more of the combined company and a bigger premium on Anglo’s current market value.

Complex proposal will need to be backed by a bigger figure to put board under real pressure