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LONDON (Reuters) - Unilever ULVR.L shareholder Columbia Threadneedle has raised concerns about the consumer goods group's decision to overhaul its structure by picking Rotterdam for its main headquarters, citing the possible impact on the company's listing on London's stock exchange.

“We’re disappointed by Unilever’s lack of engagement with shareholders ahead of its decision to restructure, particularly in view of the likely impact on its premium listing in London,” Iain Richards, head of responsible investment at top 10 Unilever shareholder Columbia Threadneedle Investments, said in a statement.

“Given the potential implications and need for 75 percent approval, they need to do more to convince UK shareholders of the merits of the move.”

Unilever UNc.AS said last week that it would make Rotterdam its sole legal base, a decision that could affect its UK listing and membership of Britain's benchmark FTSE 100 index. Index tracker funds may have sell Unilever stock if the company is removed from the FTSE 100.