The STIX (an acronym of Short Term IndeX) is a short-term market momentum indicator.
It is calculated by taking a 21 period exponential moving average of the Advance/Decline
ratio. Values over 50 are generated when there are more advancing than declining
issues, values under 50 mean more decliners. Values over 56 are considered overbought
and values over 58 are extremely overbought. Values under 45 are considered oversold
and values under 42 are extremely oversold.