Leading protection and indemnity mutuals have been moving their investment portfolios out of ­equities, to protect their finances from stock-market volatility, accord­ing to industry executives.

As a result, the clubs will probably register much lower investment returns in the coming years and will have to continue to raise premiums to break even on underwriting performance.

“We have probably all brought down the level of risk in our investment portfolios and most of us have become a lot more vanilla,” North P&I Club chief executive Paul Jennings said at...