There is a possible change coming to Bitcoin around August 1. After this time, the price will most probably go up on Bitcoin and the other cryptocurrencies as well. However, if the change occurs, people with Bitcoin on Coinbase.com or GDAX.com may find that they are not able to profit from a second coin that others will get for free.
So, to be safe, by Friday, July 28, 2017, move any Bitcoin you have on Coinbase.com or GDAX.com to Kraken.com or to a blockchain.info wallet.
ALSO, do not trade, send or withdraw any Bitcoin from July 31 to August 3.
If you want to learn more about this, you can find it here in my book