Activist hedge fund Irenic Capital Management has acquired a roughly 4% stake in UK self-storage operator Big Yellow Group, joining fellow activist Ancora Holdings in pushing the FTSE 250 company to consider a sale, according to a report by the Financial Times.

Irenic, founded by former Elliott Management investor Adam Katz and former Indaba Capital portfolio manager Andy Dodge, has been engaging with Big Yellow’s board for several months, arguing that the company is undervalued and should explore a potential sale, according to people familiar with the matter.

The move follows Ancora’s disclosure of a similar 4% holding earlier this week, making the two activist investors among Big Yellow’s largest shareholders.

Big Yellow’s shares have fallen 25% over the past year amid weakness in the UK property market, leaving the company trading near a six-year low. Its shares rose 5% on Wednesday following Ancora’s announcement, giving the business a market capitalisation of approximately £1.65bn.

The company previously attracted takeover interest from Blackstone in October 2025, although discussions ended without a deal. A formal sale process could attract interest from private equity firms and strategic buyers, according to the report.

Responding to Ancora’s demands on Thursday, Big Yellow reiterated that the previous takeover proposal did not reflect the company’s full potential, while stating that it continually assesses options to maximise shareholder value.

Irenic, which managed $2.5bn in assets at the start of 2026, has previously targeted several UK-listed companies. The hedge fund successfully campaigned for the £506m sale of Wagamama owner The Restaurant Group to Apollo and has also advocated a potential private equity sale of SSP Group, the owner of Upper Crust. It also holds a position in aerospace manufacturer Melrose Industries.

The campaign comes amid continued consolidation in UK-listed real estate, with international buyers targeting companies trading at discounted valuations.

Despite its declining share price, Big Yellow reported a 1% increase in net asset value to £13.70 per share in its latest annual results.