In the primary market, the purchase and redemption of open-end funds are usually directly sold by banks, securities and fund companies at most.

The secondary market is a trading account opened by securities companies, including closed-end funds, lof funds and etf funds.

Etf arbitrage means that when the transaction price of etf secondary market deviates from the net value of fund shares, investors can arbitrage among primary market, secondary market and stock spot market to obtain risk-free income. When the secondary market price of etf is less than the net value, buy etf in the secondary market and redeem it, and then sell the redeemed portfolio securities; When the secondary market price of etf is greater than the net value, you can buy portfolio securities in the secondary market and apply for etf shares, and then sell the obtained etf shares.