SocGen have sent a letter to clients to warn about possible gaps in pricing and liquidity surrounding the UK referendum vote.
After the SNB they've got good reason to be cautious over what is a huge event. If you were in doubt about the possible market effects surrounding Brexit then you need to get you head out of the sand.
If the banks are worried, and they provide the liquidity that your brokers feed off, then you need to be doubly sure that you're fully in control of your accounts. If you haven't checked or received information already, check your broker for any news about changes to trading conditions around the vote.
This thing is becoming such a mess that at the moment, I have no interest in trading it.