Japanese firms are the cheapest electricity stocks in the G7 — and the gap in market values is widening.

The average major electricity company in Japan is worth 10 times less than one in Europe, and 1/15th the value of one in the U.S., according to a review by Japan NRG. The market capitalization of the top American utility, NextEra Energy, is enough to buy all 10 Japanese regional power holdings — as well as the country’s top electricity wholesaler — three times over.

The differences are not due to the size of generation assets. NextEra Energy has only about 12% more capacity than TEPCO Holdings, the main supplier to the Tokyo area, but it’s 30x more valuable. NuScale Power, a U.S. firm that has yet to build a single working reactor, is worth 30% more than Kyushu Electric, utility with four reactors (total capacity 4.14 GW) online today, as well as dozens of thermal and renewables assets.

In the past twelve months, this divergence has accelerated with Japanese power utility stocks losing value, despite lower fuel costs, while peers in Europe and the U.S. gained. This potentially makes Japanese firms more of a target for M&A as well as significantly hindering their fund-raising capabilities at a time when investments in the grid and clean energy are imperative.