A top 10 shareholder of consumer goods giant Unilever has expressed concerns over company plans to move its headquarters to the Netherlands.
UK investors are worried the move, which is aiming to simplify the business into a single body in Rotterdam, would lead to the company being ejected from the FTSE 100.
If this happens, shareholders believe their stock could be sold off by passive fund managers at lower prices.
Last month, Unilever finance director Graeme Pitkethly admitted the company was "extremely unlikely" to be included in the FTSE UK series.
Investors are due to vote on the company's proposals before the end of September. Unilever needs 75 per cent of UK shareholders to vote in favour of the move, and half of investors in the Netherlands.
Iain Richards, head of governance and responsible investment at Columbia Threadneedle Investments said: "We agree that restructuring Unilever makes sense, however Unilever’s approach discriminates against UK shareholders.
"The implications are significant and Unilever hasn’t resolved the problem they've created. We need to ensure that we consider the impact and implications for our UK funds and clients.
"Unilever continues to under-estimate the significance of the problem and with the need for 75 per cent approval of the PLC shareholders they have a real challenge on their hands."