S&P 500
The broad benchmark for US equities: the largest listed companies, weighted by capitalisation in free float.
How to read the number
The world's reference point for risk appetite. Its move sets the mood for every other venue, including those that open hours earlier.
When the metric lies
Capitalisation weighting has made the index increasingly dependent on a handful of giants, so the average constituent can travel in the opposite direction to the headline number.
Also known as: spx