Two things you could do:
1. Exclude the trading folder from scans (obviously a limited risk) Standard Shield, Customize, Advanced
2. Disable the Web Shield provider which scans http web content, but I would have thought this wouldn't get in the way. Disabling the web shield would effect ALL web traffic not just your trading traffic and put your system at a greater risk than the exclusions.
Is this traffic https (I would like to hope so) ?
