Just 14 per cent of that figure, £175m, was spent on transfers between two Premier League clubs - an unforeseen outcome of the league's window closing before the rest of Europe, according to Deloitte's Tim Bridge.
The Merseyside outfit have signed AS Monaco midfielder Fabinho, RB Leipzig star Naby Keita, Stoke City playmaker Xherdan Shaqiri and AS Roma goalkeeper Alisson Becker in the summer transfer window so far.
"I'm not confident, I'm not confident and the market closes today, so is time at least for me to stop thinking about the market because the market will be closed", Mourinho said.
"Or they are investing massively like Liverpool, who are buying everything and everybody", Mourinho told MUTV after his team's 1-0 friendly loss to Bayern Munich Sunday.
"My view is that first of all is hard for me to believe we finished second", he added.
"So it's hard for me to understand or to feel or to believe that we finished second, which I keep saying that I - and sometimes it's also hard to believe - that I won eight championships and three Premier Leagues. I won eight championships and three Premier Leagues but I keep feeling the second last season was one of my biggest achievements in the game".
"So I hope I'm wrong, but I don't see them challenging for the league this year".
"Since nine years, every season - except the first when I arrived at Barcelona".
The United manager had claimed that the shortlist he handed over to executive vice-chairman Ed Woodward at the end of last season went largely ignored. The manager has to decide which way we play.
"I told that during pre-season it looked like I was saying something absolutely out of order, something insane, I repeat and maybe tomorrow the reaction is the same: Pre-season hard when you don't have your players to work, as simple as that".