David Wagner says Huddersfield can have a successful transfer window without making any signings, as long as they keep hold of their best talent.
Huddersfield have made two signings in the January transfer window so far with Alex Pritchard joining from Norwich on a three-and-a-half-year deal for a fee understood to be in the region of £12m.
Terence Kongolo also joined from Monaco on a loan deal until the end of the season.
Wagner says he is content with the club's business so far but insisted he judges the success of a window on how many of his best players he manages to keep.
Speaking ahead of Saturday's FA Cup fourth-round tie against Birmingham, Wagner said: "I think consistency is the key. Not only in [management] positions but also in the playing squad.
"For us every transfer window is successful if we are able to keep our key players. This is what we've done since I arrived.
"Every window, even without incomings, was very successful for us because we are able to keep our best players.
"We added some new players. Now it is up to us to do everything possible to help these players improve over the next five months."
Huddersfield could welcome back Philip Billing for Saturday's FA Cup tie after 12 weeks out of action with an ankle injury. Wagner likened the defender's return to the arrival of a new signing.
"Yeah, absolutely [Philip Billing] will feel like a new signing," he said.
"We have missed him while he was injured. Now he's been back in training for two and a half weeks, played 15 minutes against Bolton and another 60 for the reserves.
"Now the games come thick and fast, it is good he is back. Even if he isn't at his best fitness wise, he can catch up as best he can. He will be able to help us for sure in the coming weeks and months."