Benchmarks and the Law: Why Indices Have Their Own Rulebook

In our recent article on indices, we called them the quiet heroes of finance – the numbers that quietly decide whether your portfolio is soaring or sulking. But when an index graduates to “benchmark” status, things get serious. What looks like a harmless figure on Bloomberg suddenly comes with lawyers, regulators and compliance officers all pulling up chairs.

Benchmarks are the plumbing of modern finance. The FTSE 100, the S&P 500, SONIA, SOFR, even commodity reference prices – all of them are used to price securities, calculate loan payments and measure fund performance. Trillions of pounds hang on them. And because “trillions” is the kind of number that makes regulators spill their tea, benchmarks now come with a legal rulebook of their own.