Some of you might've noticed that certain coins on coinmarketcap.com have had their value changed quite drastically overnight, Ripple being the most obvious example for this.
If you look at the coins that have corrected, you can see that Korean exchanges where the price discrepancy has been quite notable have been excluded from the calculated mean price. Ripple was traded at $3.90 in Korea, and approximately $2.67 on non-Korean exchanges. This has led to almost 40b being removed from the entire cryptomarket's total cap overnight. This is nothing to be alarmed about.
One of the main reasons for these extreme discrepancies is due to the Korean market being quite isolated from the rest of the world, making arbitrage between the exchanges impossible on a large scale.