Brendan Rodgers says Liverpool's spending is not finished yet, with the Reds in the market for an attacking player and a defender.
Kolo Toure, Simon Mignolet, Iago Aspas and Luis Alberto all reported for the first day of pre-season on Tuesday after completing summer moves to Anfield.
And Rodgers remains in the hunt for further new recruits, with a creative player top of his list.
Shakhtar Donetsk star Henrikh Mkhitaryan has been frequently linked with a move to Anfield.
Rodgers said: "Certainly another attacking player will really benefit us, and probably another defender.
"We'll see how it develops over the course of the next few months."
Rodgers has achieved his initial target of signing players early in the summer, and the club's swift business comes on the back of January moves for Daniel Sturridge and Philippe Coutinho.
He told the club website: "It's a big thing to the club because we looked at last summer and there were lots of things that were difficult for us. That meant that the opening period of the season was difficult.
"From that we've got all our people involved, our recruitment team in - and they got to work as soon as they came in.
"We brought great signings in in January and that's really helped us. Obviously the plan was to get our signings in as soon as we possibly could - and we still hope to make a few more.
"I'm very happy with the four players I've brought in, and they'll add to the group."