Select a team in Career mode. Purchase a player who is listed for loan.
Sign the player, then go to "Budget Allocation", and set the "Transfer
Funds " to "Wage Budget" ratio 0:100. This makes the money for
transfer funds 0%. Go to "Sell Players", and terminate the loan of the
player you just signed. You should have more than $2 billion. Go to
"Budget Allocation", and change your wages funds percentage as desired
(40:60 is recommended).

During a transfer period, loan any player. Once he has signed, go into
your budget allocation, and put the entire budget into wages. Then,
release the player instantly. Go back into your budget allocation, and
put the allocation level to 50:50. You should now have over 2 billion
for transfers and 46 million for wages.