EnQuest, Serica shares fall 12% after UK oil and gas windfall tax announcement

LONDON, May 26 (Reuters) - Shares in oil and gas producers EnQuest Plc and Serica Energy Plc fell around 12% each on Thursday after the UK government announced a windfall tax on oil and gas producers.

While EnQuest has some production in Asia, both companies are mainly active in the British North Sea, producing from relatively mature fields.

"The impact, given the investment allowance offset included with the tax, is most for those companies with low capex compared to EBITDAX, which includes Serica," Stifel analysts said in a note, referring to an acronym for core profit.

They assume the new tax will cost Serica around 290 million pounds ($364.65 million) between 2022 and 2024 and shave around 100 pence per share off Serica's stock value.

Unlike other taxes, the new 25% additional levy on oil and gas profits, according to a Treasury fact sheet, cannot be offset against so-called tax losses, of which EnQuest has around $3 billion, or diminished by decommissioning spending.

EnQuest shares on Thursday hit a session low of 30.35 pence, a two-month low. It was the company's biggest daily percentage drop since November 2021.

Serica shares hit their lowest level in three months.

The share prices of other big oil and gas producers in the North Sea, such as Harbour Energy, did not slump on Thursday, possibly as their bigger investment plans can buffer some of the new tax burden.

Similarly, shares in oil majors BP Plc and Shell shrugged off the tax announcement as their global operations and activities from wellhead and wind farms to serving coffee in petrol stations lessen their exposure to the new British tax. ($1 = 0.7953 pound)