Rental stock is down 40% on a year ago across the haart chain.
CEO Paul Smith blamed the number of restrictions and additional costs being “heaped” on landlords, saying that they are “certainly taking effect on the lettings market”.
With supply down, rents have been pushed up 5% in the 12 months to the end of April.
Haart also reported that the number of sales to buy-to-let investors is down 20.9% across England and Wales, while the number of tenants entering the market is up by 18% year on year.
On the sales side, haart said it had registered almost 40% new buyers this April than in the same month a year ago.
However, despite a monthly improvement, Smith said that supply was still hovering below pre-EU referendum levels.