Celtic have completed the signing of left-back Greg Taylor while Rangers are set to announce the return of Ryan Kent.
Scotland left-back Taylor has signed a four-year contract after Celtic reached a deal with Kilmarnock for the 21-year-old.
Taylor told Celtic’s website: “It’s been a whirlwind of a day but I’m over the moon to be here and thankfully that’s it over the line.
“As soon as I knew of Celtic’s interest, I was desperate to come, so it’s been a great day, certainly now that it’s done.”
Rangers have agreed to pay a fee of about £7million for Liverpool winger Kent after the 22-year-old spent the summer in limbo.
The Reds refused to sanction a second loan move to Ibrox but Rangers bided their time, however their hand was forced when Club Brugge made a move for the winger.
Manager Steven Gerrard had claimed on Sunday that any incoming transfer would have to come “out of the blue”.
The Ibrox club have moved on three players. Summer signing Jake Hastie has joined Rotherham on a season-long loan; Graham Dorrans agreed a deal to tear up his Gers contract; and midfielder Jason Holt has moved to St Johnstone on loan for the season.
Celtic have loaned out three players. Right-back Anthony Ralston has gone to St Johnstone, forward Jack Aitchison has joined Forest Green and midfielder Ewan Henderson moved to Ross County, who have released Davis Keillor-Dunn.
The Hoops have also been linked with deals for two teenage full-backs from Premier League clubs – Jeremie Frimpong of Manchester City and Manchester United’s Lee O’Connor.
Motherwell have signed former Kilmarnock and Dundee midfielder Mark O’Hara on a season-long loan from Peterborough.
Fir Park left-back Adam Livingstone joined Morton on loan, while attacking midfielder Craig Tanner rejected the offer of a four-month contract extension after recovering from a serious knee injury.
Kilmarnock were linked with a number of players including O’Hara, Celtic pair Jack Hendry and Calvin Miller, Scotland Under-21 and Venezia forward Harvey St Clair, Wolves defender Connor Johnson and Dundee United striker Osman Sow.
But the only pieces of confirmed business at Rugby Park going into the final 90 minutes of the window were the departure of Taylor and Kirk Broadfoot after the defender was released from his contract.
Hamilton have signed 22-year-old German attacking midfielder Adrian Beck from Union Saint-Gilloise in the Belgian second tier on a season-long loan.
Livingston announced the departure of former Rangers winger Gregg Wylde while Hibernian were linked with a move for Peterborough right-back Jason Naismith.
St Johnstone released midfielder Kyle McClean while St Mirren loaned defender Jack Baird to Morton until January.
Scots on the move in England included former Rangers and Hibernian striker Jason Cummings, who moved from Nottingham Forest to Shrewsbury for an undisclosed fee, and former Hamilton midfielder Ali Crawford, who signed for Bolton from Doncaster.