A bond portfolio strategy in which the portfolio is designed to have approximately equal amounts invested in every maturity within a given range. With this approach, bonds in the portfolio are evenly distributed between short term, intermediate term, and long term maturities. As short term bonds expire, the funds received from these are reinvested in long term bonds. Thus, the portfolio gradually evolves with longer term bonds becoming intermediate and then finally shorter term bonds.
This type of portfolio strategy is relatively easy and inexpensive to administer. Transaction costs are minimized, and the portfolio manager is not required to spend time constantly buying and selling bonds.