Shares in some of the UK’s biggest buy-to-let lenders such as Paragon and One Savings Bank have fallen after it emerged that the chancellor may make private landlords commit to a one-year rent freeze.

In an effort to protect households from rising living costs as a result of the Iran war, Rachel Reeves is considering whether to ban landlords in England from increasing rents for a limited period of time, the Guardian revealed on Monday night.

Shares in buy-to-let lenders fell when the London Stock Exchange opened on Tuesday.

Stock in OSB Group, one of the UK’s biggest buy-to-let mortgage providers, was down 3.6% at 510p as investors worried the rent freeze would hurt the FTSE 250 company behind the lenders Kent Reliance and Precise Mortgages.

Shares in Paragon Banking Group, another large buy-to-let lender, slumped 2.4% to 733p. The FTSE 250 group is largely focused on lending to professional landlords who own more than three properties.

The Treasury said last night it would not comment on “speculation” about the proposal. However, Bridget Phillipson, the education secretary told Times Radio this morning: “That isn’t something that we are actively considering, just to be completely clear, that is not the approach we will be taking. But the chancellor is concerned, as we all are, about the impact of the conflict in the Middle East on family finances and is looking at what more might be required to help get through this.”

The rent freeze would be the latest in a line of restrictive measures imposed on private landlords by successive governments since 2015 in a bid to crack down on the once booming buy-to-let sector.

On Friday, the Renters’ Rights Act will come into force, bringing significant changes to the sector. The new law aims to give renters more security by banning no-fault evictions, limiting rent rises to once a year and only up to “the market rate”, and stopping landlords from accepting an offer over asking price.

Timothy Douglas, the head of policy and campaigns at Propertymark, which represents property agents, said the reports of a rent freeze were “alarming” for landlords when the Renters’ Right Act is already introducing “huge regulatory change”.

He added: “Rent controls risk distorting the market and undermining investment at a time when demand already far outstrips supply.”

Douglas said the government should instead focus on increasing housing supply and supporting long-term investment in the private rented sector.

In September 2022, Nicola Sturgeon, the then first minister of Scotland, introduced a rent freeze for tenants living in social and privately rented homes in an attempt to ease the cost of living crisis. This stopped in April 2023 when increases were capped at 3% for 12 months.