Two more exchanges, OKCoin and itBit, have been added to CoinDesk’s USD Bitcoin Price Index.

These additions will be live as of 15:00 GMT today, the 25th November.

Both exchanges see a significant amount of USD-BTC trade. OKCoin‘s US dollar trading volume over the 30-day period ended 11th November stood at 280,279 BTC. This figure amounts to 17.44% of the total volume on exchanges tracked by the BPI, according to data from Bitcoinity.org.

The same measure for itBit stood at 57,727 BTC, or 4.17% of total volume.

The other exchanges tracked by the BPI are Bitstamp, Bitfinex, BTC-e and LakeBTC, with a total volume of 1,327,182 BTC for the same 30-day period.

CoinDesk has adjusted its criteria for inclusion in the BPI. One of the conditions for inclusion is that bitcoin transfers into or out of the exchange must be completed within 24 hours. This criteria has been adjusted to allow bitcoin transfers to take up to two business days.

The adjustment allows a wider range of exchanges with a significant share of volume who meet the other criteria to be considered for inclusion.

To reiterate, the rest of the criteria include:

USD exchanges must serve an international customer base. Exchange must provide a bid-offer spread for an immediate sale (offer) and an immediate purchase (bid). Minimum trade size must be less than 1,500 USD (9,000 CNY) or equivalent. Daily trading volume must meet minimum acceptable levels as determined by CoinDesk. Exchange must represent at least 2% of the total 30-day cumulative volume for all of the exchanges included in the BPI.

Correction: A previous version of this article mentioned inclusion for ‘fiat transfers’ in the BPI. This has been corrected to ‘bitcoin transfers’.