West Ham United's owners, David Gold and David Sullivan, injected £35 million into the club following their relegation to the Championship in 2011.
Accounts for last season have revealed the level of investment by Gold and Sullivan during the 2011-12 as West Ham secured their return to the Premier League via the Championship play-offs.
Turnover during that period fell by £34.4 million to £46.25 million following the loss of television and sponsorship income totalling £26.5 million.
Sullivan explained his and Gold's £35 million loan - £3 million of which has been invested this season - was undertaken to fast-track a "three-point strategic plan".
"Both myself and my partner David Gold decided to invest our money into achieving promotion and during the season we invested a further £32.2 million of our cash in order to allow the manager to go into the transfer market and buy the players we needed to secure promotion," Sullivan wrote in his chairman's statement.
"During that period we brought or loaned 18 players, most notably Kevin Nolan, Matthew Taylor and Ricardo Vaz Te, investing a total of £17.1m."
Since earning promotion West Ham have signed the likes of Modibo Maiga, James Collins, Alou Diarra and Matt Jarvis in their bid to secure their top-flight status.
Information from the Press Association was used in this report.