SSE, British Gas owner Centrica and Drax topped their respective indices as a spokesman for Boris Johnson confirmed the windfall tax would not be extended to include electricity generators.
“We would not seek to make any new policies or major fiscal decisions. So there are no plans to do that,” according to Reuters quoting a spokesperson for the soon-to be ex-PM.
SSE jumped 2.9% to 1,743p and Centrica was 2.7% higher at 82.2p, to occupy the top two positions on the FTSE 100.
FTSE 250-listed Drax saw the best of the gains, rising 6% to 697p.
“We will continue to evaluate the scale of the profits and consider appropriate steps but there are no plans to introduce or extend that to that group," said the spokesperson.