The phrase "suspicious activity" means behavior or actions that seem strange, unusual, or questionable. It is used to describe situations or individuals that might be involved in illegal, dangerous, or dishonest activities. Full definition
Your obligation to report suspicious activity depends on your jurisdiction. (nar.realtor)
It would reduce the requirements for suspicious activity reports and grant immunity from federal criminal prosecution or investigation simply for providing financial services to a legal marijuana - related business. (cnbc.com)
If there is something and you haven't made any changes, definitely take a closer look — this could be indicative of some sort of suspicious activity on your account. (howtogeek.com)