This measures the share price vs. the 200 Day Moving Average (200d MA) expressed as a percentage difference. A negative number indicates a share price trading below the 200d MA
The 200d MA is a long term moving average calculated by dividing the sum of the security's average closing price over the last 200 days by 200.
The 200-day moving average is a popular technical indicator which investors use to analyse price trends. A stock that is trading above its 200 Day Moving Average is considered to be in a long term uptrend.
If the short term (50 day) Moving Average breaks below the long-term (200 Day) Moving Average, this is known as a Death Cross, whereas the inverse is known as a Golden Cross.