Hardened racing fans are used to the sight of weights being added to the fastest racehorses to even up the chances of the field, but few expected to see something similar happening in the market for corporate bond funds.

Once-favourite fund managers, including New Star Asset Management and Old Mutual Asset Managers, find themselves weighed down by the investments they made in bonds issued by banks. They are being overtaken by rivals including M&G, Schroders and Invesco Perpetual.