Former US regulator explain Barclays' $453m fine

US regulators have upheld a fine on Barclays and four of its traders of $453m (£300m) for allegedly manipulating electricity prices.

Barclays must pay $435m within 30 days, while one trader must pay $15m and three others $1m each.

Barclays denies wrongdoing and says it will vigorously defend itself. But what is the fine actually for?

Susan Court is the former Director of Enforcement at the Federal Energy Regulatory Commission (FERC) - the regulator that has ordered the fine.

She told BBC Radio 5 live's Phil Williams, "If a company or an individual is conducting itself... in such a way as to defraud that market, then the commission's jurisdiction is triggered and they have a responsibility to prevent that."