Buy undervalued Grade A, hold it for a long time, and obtain stable interest income. Grade A is usually a discount transaction, and the difference between the agreed rate of return and discounted cash is isomorphic to form the income source of Grade A, that is, the implied rate of return. By purchasing Grade A with high implied yield and holding it for a long time, the principal security and interest income can be guaranteed relatively stably. Look for undervalued and overall discounted A shares and rotate them. Calculate the discount rate of the parent fund and the implied rate of return of Grade A every weekend, and choose Grade A with high implied rate of return and high discount rate of the parent fund. Buy three Grade A with high ranking and good liquidity every week, and rotate every week. Buy Grade A with discount expectation and get discount income. For index-based graded funds with no duration, there is a basic feature worthy of attention, that is, their A shares are basically discounted transactions in the market, while their B shares are premium transactions. This discount phenomenon mainly stems from the fact that A shares have no redemption mechanism. According to the design of graded funds, it is impossible for investors to redeem the net value of A shares directly. Even if it is converted on a regular basis, they can only cash in the agreed income, that is, the loan "interest" given by B share, and their net value still cannot be cashed. Of course, the graded fund has also designed a matching conversion mechanism. The holders of share A can increase their share B according to the corresponding proportion, and then apply for merger into a basic share, namely the parent fund. Finally, the net value of the parent fund can be redeemed through the redemption mechanism. In this way, it seems that share A can be cashed out in net value, but in order to achieve this goal, investors must increase their purchases of share B in a corresponding proportion. In addition to the need to increase funds, investors must also bear certain market risks, because the process from applying for merger to selling takes two trading days. As long as the securities market is trading, it will change, and the holders of A shares hope to cash in the net value of A shares on that day. Once two trading days have passed, the net value of the carrier parent fund used for cashing may change, and investors inadvertently increase the market risk, so the failure to redeem the net value in time is an important factor in the discount trading of A shares.