I understand that CoinBase has weekly buy and sell limits. Does GDAX have this as well?
From the GDAX support page (source):
Deposit (BTC, ETH, LTC): Unlimited
Deposit (ACH or SEPA): Varies
Deposit (USD via wire): Unlimited
Withdrawal: $10,000/day for individual accounts and $50,000/day for institutional accounts. To be considered for higher withdrawal limits, please go to your Settings within GDAX and click "Increase Limits."