Utilize your financial knowledge, give your answer or opinion to the input question or subject . Answer format is not limited.

No transaction fee ETF trades - what's the catch?
what is the mechanism by which they   make money on the funds that I have in   my account? Risk drives TD Ameritrade to look for profits, Turukawa's storytelling about 100,000$ and 500$ is trivial. The risk consists of credit risk, asset-liability risk and profit risk. The third, based on Pareto Principle, explains the loss-harvesting. The pareto distribution is used in all kind of decentralized systems such as Web, business and -- if I am not totally wrong -- the profit risk is a thing that some authorities require firms to investigate, hopefully someone could explain you more about it. You can visualize the distribution with rpareto(n, shape, scale) in R Statistics -program (free). Wikipedia's a bit populist description: In the financial services industry,   this concept is known as profit risk,   where 20% or fewer of a company's   customers are generating positive   income while 80% or more are costing   the company money. Read more about it here and about the risk here.