Libor, the nearly 50-year-old global borrowing benchmark that became a byword for corruption, is headed for the trash heap of history.

The U.K. Financial Conduct Authority will phase out the key interest-rate indicator by the end of 2021 after it became clear there wasn't enough meaningful data to sustain the benchmark that underpins more than $350 trillion in securities, Andrew Bailey, the head of the regulator, said in a speech Thursday at Bloomberg's London office.

The end of the London interbank offered rate, or Libor, is welcome on many levels for regulators. It was tied to some of the banking industry's biggest scandals, leading to about $9 billion in fines and the conviction of several bankers for manipulating the rate. Relying on the opinions of industry insiders to set the daily estimates based on interbank lending, some in markets that saw fewer than 20 transactions annually, was unacceptable, Bailey said.