David Abraham, the Channel 4 chief executive, said that consolidation in the UK production sector has resulted in a number of dominant super-indies, such as All3Media, Shine and Endemol UK.
Despite noting that much of Channel 4's best programming comes from these firms, Abraham said that the broadcaster must also protect its "uniqueness" by supporting "those parts of the creative culture that other broadcasters cannot or dare not visit".
Speaking at the Nations & Regions conference in Salford, Abraham said: "This is not to criticise the larger indies, which make some of our best shows, but I think it's fair to say that in recent years we may have become too reliant on too narrow a range of companies.
"In a sector where we estimate that roughly 70% of turnover is in the hands of the so-called super-indies, this is a special challenge for us. There's no question that, since consolidation started, an increasing proportion of spend has gone to the channel's top 10 suppliers."
Abraham said that Channel 4 must "ensure no new or emerging company, individual talent or brilliantly authored piece is locked out because the balance between the reliable and the high-risk has tipped too much in the former's favour".
Channel 4 is therefore setting up a new £2 million "innovation and authorship" fund, called the Alpha Fund, which will support the "very first stages of creative ideas".
Abraham noted that the likes of filmmaker Shane Meadows and comedian Peter Kay were supported in the 1990s with similar types of grassroots creative funding.
He also confirmed that the broadcaster will make a further £2m available this year for convergence projects, aimed at developing "ideas, apps and creative concepts for the next generation of connected-TV like YouView".