The £23 million fee has been agreed to after two previous bids were rejected by the Potters. The deal would break the West Ham club record of £20 million which was paid last year for Andre Ayew from Swansea.
This would bring West Ham a left sided winger which the team has been searching for as Michail Antonio, Andre Ayew, Sofiane Feghouli, and Robert Snodgrass all prefer to play on the right side.
Arnautovic would be the third signing of the summer after Pablo Zabaletta and Joe Hart joined the Hammers from Manchester City. The Joe Hart deal just needs to be announced by the club but the deal is done.
This just leaves the striker situation to be dealt with but with Zabaletta joining on a free and the Joe Hart deal as a loan, West Ham should have enough left in the transfer pool to make a move for Javier Hernandez.