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

How to rebalance a portfolio without moving money into losing investments
Also, almost by definition rebalancing involves making more trades   than you would have otherwise; wouldn't the additional trading fees   you incurred in doing so reduce the benefits of this strategy? You forgot to mention taxes. Rebalancing does or rather can incur costs. One way to minimize the costs is to use the parts of the portfolio that have essentially zero cost of moving. These generally are the funds in your retirement accounts. In the United States they can be in IRAs or 401Ks; they can be regular or Roth. Selling winners withing the structure of the plan doesn't trigger capital gains taxes, and many have funds within them that have zero loads.  Another way to reduce trading fees is to only rebalance once a year or once every two years; or by setting a limit on how far out of balance. For example don't rebalance at 61/39 to get back to 60/40 even if it has been two years.  Given that the ratio of investments is often rather arbitrary to begin   with, how do I know whether I'm selling high and buying low or just   obstinately sticking with a losing asset ratio? The ratio used in an example or in an article may be arbitrary, but your desired ratio isn't arbitrary. You selected the ratio of your investments based on several criteria: your age, your time horizon, your goals for the money, how comfortable you are with risk. As these change during your investing career those ratios would also morph. But they aren't arbitrary.  These decisions to rebalance are separate from the ones to sell a particular investment. You could sell Computer Company X because of how it is performing, and buy stock in Technology Company Y because you think it has a better chance of growing. That transaction would not be a re-balancing. Selling part of your stock in Domestic Company A to buy stock in international Company B would be part of a re-balancing.