An all-time high refers to the highest level reached by a particular financial asset or index over its entire history.
It is a crucial metric for investors and traders, as it provides a benchmark against which to measure the performance of an asset.
For example, the all-time high for the S&P 500 index is a point in time when the index reached its highest value. Similarly, the all-time high for a particular stock refers to the highest price that the stock has ever traded at.
Achieving an all-time high is considered a significant milestone for an asset, and it can often attract a lot of attention from investors and analysts. It can also signal positive sentiment and a bullish market outlook.