With the recent volatility in Tether; I have quickly put together an overlay indicator that shows the mid-point between Open & Close price using the following tickers:
KRAKEN:USDTUSD
POLONIEX:USDTUSD
BITTREX:USDTUSD
HITBTC:USDTUSD
POLONIEX:USDTUSDC
HITBTC:USDUSDC
Each of these is weighted based on their volume in comparison to the total combined volume (that is, higher volume traded symbols hold the most value in the calculation).
This is helpful to be able to quickly check for "true" USD value; rather than a Tether proportioned calculation.