Reading boss Brian McDermott will reportedly be handed a transfer budget of £15m this summer after the takeover by Russian tycoon Anton Zingarevich.
The businessman agreed to buy 51% of the Royals in January, and it has been speculated that he is prepared to heavily invest this summer.
A statement released by the club said: "Reading Football Club are pleased to announce that a 51% acquisition by Thames Sports Investment (owned by Anton Zingarevich) has now been completed, complying with all Premier League and Football League requirements.
"Four additional directors have been added to the Reading Football Club board chaired by Sir John Madejski, namely Anton Zingarevich, Christopher Samuelson, Andrew Obolensky and chief executive Nigel Howe. Ian Wood-Smith also remains a director.
"The football club and TSI would like to thank both the Premier League and Football League for their assistance, and we now enter another bright new era for our historic club, back in the Barclays Premier League."
Reading won the Championship title last season.
