Yup. In short, when an entity (whether they are a person or a business) transacts in an amount of more than $10K in cash the bank is required to file a CTR with FinCEN, the Financial Crimes Enforcement Network. In the olden days, the CTR would be filed if a single transaction met the threshold. As technology evolved the law evolved and banks are now required to aggregate transactions. When an entity tries to create a series of transactions in a way that would avoid reporting, which is called "structuring," the bank is required to file a Suspicious Activity Referral.
The initial reason was to deter money laundering, which often occurred in conjunction with organized crime activities and drug dealing. After the 2001 terror attacks it became known as a way to detect and deter the financing of terrorism.
Wikipedia has a decent explanation in layman's terms.