The competition watchdog has given the green light to an energy supply merger that will shrink the Big Six companies down to five. The Competition and Markets Authority (CMA) said the combination of SSE’s supply arm with Npower would not dampen competition in the energy market. The number of people switching their energy supplier is the highest it has been in 10 years, spurred by a boom in energy start-ups joining the market. However, political worries persist because many people remain on standard variable tariffs (SVTs), which are typically higher in price than fixed deals.