Knight Vinke renewed its assault on HSBC's strategy today, saying that Britain's biggest bank was regarded by many shareholders as a disparate collection of poorly connected business trying to be all things to all people.

The activist fund manager, which has the full backing of Calpers, the powerful California pension fund, also blasted the bank for its handling of the US sub-prime implosion, saying that the market had failed to take fully into account the risk being taken on to the HSBC balance sheet.

In another broadside, it accused the board of using "unclear and possibly misleading language" in describing an executive bonus plan that had the flaw of rewarding executives even in cases where shareholders were no better off.

It said that its concerns were shared by other institutional investors, with ten having so far contacted Knight Vinke asking for a meeting or more details of its case since it announced its campaign on Friday.

HSBC had failed to achieve market leadership in any market outside Hong Kong and had failed to exploit synergies, with most of its individual country businesses run as independent silos, it said.

"As a consequence, we believe that many investors ... still regard HSBC effectively as a holding company for a collection of disparate and poorly connected business which ... generally lack scale," it said in a letter to Stephen Green, the HSBC chairman.

There was a perception that "HSBC lacks focus and that the 'world's local bank' is seeking to be all things to all people".

HSBC said today: "We speak to hundreds of major investors every year. The feedback they give us is that they are understanding and supportive of our strategy."

Several UK institutions regard the campaign as unnecessary, arguing that HSBC has already shifted its strategic focus back to emerging markets, and that given the more risk-averse markets of the past few weeks, the criticism is badly timed.

Together, Knight Vinke and Calpers own £192 million of HSBC stock, with options over a further 13.2 million shares.

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