The Premier League window is closing earlier this year but clubs in Scotland and most of the big European leagues have until August 31 to do their business.
Some critics have said this gives European clubs an advantage over English teams as they know they are desperate to push moves through quickly and may be willing to pay over the odds for a player.
So here are some of the big moves to watch out for today.
Thibaut Courtois — Chelsea to Real Madrid
On Wednesday, August 8, Chelsea broke the world transfer record for a goalkeeper when they splashed out £71.6 million ($92.3 million) on Kepa Arrizabalaga from Athletic Bilbao in Spain.
Kepa, 23, arrives at Stamford Bridge after the Blues triggered a release clause in his contract.
Few people outside Spain have ever heard of him but Chelsea knew they needed a new keeper because the Belgian international Thibaut Courtois has lined up a move to Real Madrid, which should go through on Thursday, August 9.
Kepa's signing smashes the goalkeeper transfer record which was set only a few weeks ago when Liverpool signed Brazilian keeper Alisson from Roma for £66.8m.
Bizarrely Courtois is expected to move for considerably less, despite him being one of the best keepers in the world who has been tried and tested in the Premier League.
Courtois, 26, has played 278 games, compared with Kepa's 53.
Harry Maguire — Leicester to Manchester United
England defender Harry Maguire outshone many of the world's best defenders at the World Cup in Russia last month.
An incredible journey. The highs and the lows… the joys of football. Massive thankyou for your support throughout. Special mention to the manager for giving me this opportunity. @England 🏴🦁❤️ pic.twitter.com/YfWceqrIiL— Harry Maguire (@HarryMaguire93) 14 July 2018
On Monday, August 6, it was reported Manchester United were ready to offer more than £75 million ($97.4 million) to sign Maguire from Leicester City.
That would make him the priciest defender in the history of football.
But Leicester have given no sign of wanting to sell and the 25-year-old, who only joined the club from Hull City last summer, has also not indicated a willingness to move to Old Trafford.
Maguire is one of three footballing brothers from Sheffield. He began his career at Sheffield United and at the weekend tweeted about going to watch his younger brother Laurence playing for Chesterfield, in the fifth tier of English football.
During the 2016 transfer window Manchester United set a global transfer record by splurging a whopping £93.2 million ($121 million) to sign Paul Pogba who won the 2018 World Cup playing for France.
But if they are going to sign Maguire they are leaving it very late.
Jack Grealish — Aston Villa to Tottenham Hotspur
Tottenham Hotspur are the only club in the "Big Six" who have sat on their hands this summer and refused to spend any money.
Chairman David Levy is notoriously frugal and drives a hard bargain so it was no surprise when it emerged earlier this week that Tottenham and Aston Villa were £7 million ($9 million) apart in their valuation of midfielder Jack Grealish.
Jack Grealish is the most overhyped football player, ever.— Lewy_himself 🐺🔶⚫️ (@lewypoo92) 7 August 2018
His career with villa:
Barry Douglas last season:
Sold for £3million to Leeds.
Barry Douglas is a left back 😂
Birmingham-born Grealish has been with Villa since he was a schoolboy and it would be a massive wrench for him to leave but they are in the Championship while Spurs are in the Premier League and the Champions League.
Rumor has it that Spurs have offered £25 million ($32 million) and Villa want at least £30 million ($39 million).
Whether Levy caves in and pays up on Thursday remains to be seen.
Wilfred Zaha — Crystal Palace to Tottenham
Another player Spurs have had their eye on all summer is Crystal Palace's pacy front man Wilfred Zaha.
Again his club, Crystal Palace, have slapped a prohibitive price tag on him which David Levy has been unwilling to meet.
I’m a big fan of Wilfred Zaha!! Every time he plays against @ChelseaFC he often scores and plays brilliantly. Would you guys want him at Chelsea? #CFC— Chelsea FC Fan Club (@ConteBlueArmy) 3 August 2018
RT:- Yes would be a great signing
Like:- No, rather we buy someone else. pic.twitter.com/Y2BxXXAAWD
Zaha, who had an unsuccessful spell at Manchester United a few years ago, is said to want to join a bigger club and will be hoping Spurs agree to stump up the cash required.
Chelsea are also monitoring Zaha's situation and could move for him before 5pm.
Toby Alderweireld — Tottenham to Manchester United
Tottenham also have several players who are reportedly unhappy at the club and want to move on.
One is England full back Danny Rose, who has many admirers but has had a number of training ground spats with manager Mauricio Pochettino.
Another is the Belgian international defender Toby Alderweireld, a player who Manchester United boss Jose Mourinho has long admired.
If Mourinho cannot get Maguire he could be tempted to go back in for Alderweireld, who starred for Belgium as they made it to the semi-finals of the World Cup in Russia.
A third option would be to buy Jerome Boateng, a former Manchester City defender, who now plays for Bayern Munich.
Boateng was in the Germany squad which flopped at the World Cup.