West Ham co-owners David Sullivan and David Gold have today increased their stake in the Barclays Premier League club to 60%.
Sullivan and Gold, who previously owned Birmingham, bought the Hammers from financially-stricken Icelandic group CB Holdings in January.
Today they have both increased their share of the club from 25% to 30% at a cost of £8million, with £4million going to CB Holdings and the other half to the club.
Sullivan said in a statement on the club website, www.whufc.com: "Myself and David Gold are, like you, West Ham United fans and our aim is to ensure our club enjoys a stable and successful future.
"To this end, we have both invested a further £4million to increase our shareholding to 30% each."
Sullivan and Gold made public the scale of West Ham's financial problems following their takeover, putting a £110million figure on the club's debts.
Their relationship with manager Gianfranco Zola also came under the spotlight, with Sullivan describing the 3-1 defeat by Wolves in March as "pathetic".
Zola kept the Hammers in the Premier League but was sacked on May 11, with Avram Grant expected to be named as the Italian's successor following his resignation as Portsmouth boss.
CB Holdings still own 40% of the club but Sullivan and Gold have a three-year option to buy those shares while they have also been seeking external investment.
Sullivan continued: "We have a long-term intention of increasing our shareholding, while we have also invited professional investors to share in our vision for this special club.
"Also, in the near future we hope to extend to supporters the opportunity to invest in the club.
"We are committed to putting West Ham on a firm financial footing that will form the basis, we hope, for success both on and off the pitch."
The club also revealed the £4million received in today's deal will "bridge the gap" in the Hammers' finances.