British PM Theresa May vows energy price cap if re-elected

British Prime Minister Theresa May pledged on Tuesday to cap household energy prices if she is re-elected on June 8, sending stocks tumbling with the biggest market intervention since the sector was privatized almost 30 years ago. Energy bills have doubled in Britain over the past decade to about 1,200 pounds ($1,500) a year, putting the biggest providers in the sights of politicians and voters who are already battling rising inflation and limited wage growth.

May, from the center-right Conservative Party, has previously praised free markets. But she has also warned that she would intervene in industries deemed to be dysfunctional. She said on Tuesday a move to cap energy standard variable tariffs would help about 17 million families. "Like millions of working families, I am fed up with rip-off energy prices," she wrote in the Sun newspaper, the country's biggest selling title. "I expect (this) to save families on poor value tariffs as much as 100 pounds."

The British market is dominated by six big providers - Centrica (CNA.L), SSE (SSE.L), Scottish Power (IBE.MC), Npower (IGY.DE), E.ON (EONGn.DE) and EDF Energy (EDF.PA) - which account for about 85 percent of the retail electricity market. The number of consumers switching suppliers rose to a record high last year and the big six providers held 99 percent of the market just five years ago, showing competition is improving. But an investigation by the competition watchdog in 2016 said households had overpaid 1.4 billion pounds a year in the previous three years due to uncompetitive standard tariffs.

Shares in Centrica (CNA.L), which owns household energy supplier British Gas, fell as much as 5 percent in early trading, adding to the 10 percent fall recorded since the start of the year. SSE (SSE.L) fell as much as 3 percent.

Analysts at RBC Capital Markets said the main reason for Tuesday's share price reaction was that May said the cap would apply to all standard tariffs, rather than just those customers deemed as vulnerable, as previously expected. The industry has argued that a price cap would wipe out competition and damage investment.

Centrica Chief Executive Iain Conn said last month the plan suggested some in May's government did not believe in free markets. Energy prices could go up under Theresa May's plans, the Business Secretary has admitted – despite the party's pledge to save families £100 a year.

Greg Clark acknowledged that the flagship policy to 'cap' bills would leave the energy regulator free to let them rise, if international prices went up.

The concession came as the trade association Energy UK tore into the Prime Minister's plans, warning it would prevent people saving money by switching provider.