Professional services account for a large portion of the United Station economy, producing about $600 billion in annual revenue for 600,000 individual firms. Legal service make up the largest chunk at $130 billion followed by engineering services ($120 billion); computer-related services ($110 billion); accounting ($60 billion); management consulting ($60 billion); advertising ($50 billion); and scientific research ($25 billion). If included, brokerage services, would add another $200 billion of revenue. This subsector includes securities brokerage ($80 billion), insurance brokerage ($60 billion), and real estate brokerage ($40 billion).
The majority of all professional firms are small. In fact, the vast majority operate from a single office. Only about 5,000 firms have annual revenue over $10 million.
