Liverpool have signed Hull’s Andrew Robertson in an initial £8m deal, with Kevin Stewart going the other way for what is thought to be a similar fee.
Scotland left-back Robertson, 23, joins on what the Reds describe as a “long-term contract” for a fee which could rise to £10m.
Midfielder Stewart, 23, signs a three-year deal with the Championship club.
Robertson said: “It feels a bit surreal. There are not more special clubs than Liverpool.”
The defender joined Hull from Dundee United for £2.85m in 2014 and made 39 appearances last season as the Tigers were relegated from the Premier League.
He added: “When you grow up as a kid you dream of playing with big clubs such as Liverpool and to make that a reality is a dream come true for me.
“I just want to prove to people that I can do it at this level, and hopefully I manage to do that this season and do good things for this club.”
Liverpool manager Jurgen Klopp added: “For Andrew, this is another big step on what has been a quite incredible personal journey in a very short space of time.
“I know our environment will benefit him and help him push himself even more than he has already. This is a player who does not limit his ambition.”
United will receive about £600,000 from the deal – paid over the next two or three years – as a sell-on clause for a player they signed from amateur club Queen’s Park in 2013.
Robertson is Liverpool’s third summer signing following the arrival of Roma winger Mohamed Salah and Chelsea striker Dominic Solanke.