High Trade Profits

In other terms, productivity gains determine rising profits.

High trade profits can prompt other people to entry the market and begin to compete with current traders. In manufacture, this effect, although still present, crucially depends on the easy of imitation of product features and production processes. It's often difficult to enter into highly profitable markets.

If markets were all perfectly competitive in their long run equilibrium, all firms in the economy would have the same constant level of profits: zero. By contrast, in the real world, firms have different profits with certain sectors and certain firms systematically reaching better profits than others.

This is due to ubiquitous imperfect competition, barriers to entry, innovation and product differentiation.