
NASDAQ has announced that both indices are calculated using data from multiple cryptocurrency exchanges “to provide a single price point for BTC and ETH. The BLX is one of the most widely-referenced BTC indices among crypto traders and has been calculated back to 2010. Likewise, the ELX has been calculated back to 2014.”
Nasdaq will be basing the prices from 50 bitcoin sources globally which are considerably higher than other exchanges like CBOE and CME Group.