Ftse 100
In short
The FTSE 100 is a stock market index that tracks the performance of the 100 largest companies listed on the London Stock Exchange.
In plain words
It acts like a thermometer for the UK's biggest businesses. When the index goes up, it means the share prices of these top companies are generally rising. It is often called the 'Footsie'.
A simple example
If most of the big companies like Shell or HSBC see their share prices increase on a Tuesday, the FTSE 100 index value will also go up.
Why it matters
Investors use it to judge the health of the UK economy and the British stock market. It is a key indicator used by news outlets and financial experts worldwide.
Easy to mix up
Do not confuse it with the FTSE 250, which tracks medium-sized companies rather than the largest ones.