Shares in home delivery grocer Ocado have fallen more than 10% after the John Lewis pension trust sold its 10.4% stake in the firm for £152m.
The online company said the sale would not affect its commercial relations with Waitrose, a John Lewis division.
Ocado mainly sells Waitrose products, but some analysts expect the two to become competitors as John Lewis expands its own grocery business.
Ocado shares floated in July have risen particularly strongly since November.
The company had a market value of about £1.4bn, but its shares ended Friday were down 30p at 255p.
In a statement, John Lewis said it had arranged for investment bank Goldman Sachs to sell its entire holding of 57.3 million shares to a range of institutional investors. The price paid was 265p a share, raising about £151.8m.
The John Lewis pension fund sold more than half its original stake in Ocado at the time of the online grocer's initial public offering in July.
There had been a "lock-in" agreement preventing further share sales, which expired last month.
The pension trust's representative on Ocado's board, Patrick Lewis, has resigned.