Infiltration, espionage, sabotage, and manipulation of rivals, partners, and other key influential entities. If that fails or seems ineffective threaten/harass/assault (it helped that there was always a fleet of nerds with digital spaceships to call upon heh).

One example would be having an "alt" character be accepted into a rival group, and then just monitor their private chats and asset listings (through that API) for any opportunities to act upon. Think resource transports, infrastructure vulnerabilities, strategic assets mistakenly placed in generally accessible storage, etc.

So really quite similar to how these things work in real life, and nothing that directly involves any trading in and by itself. Mostly market and environment control for better success rates and increased profit margins, but at lower cost and with more leeway for mistakes/timings.