What is a common characteristic of open-end investment companies?

Open-end investment companies, commonly known as mutual funds, typically allow investors to redeem shares at any time. This characteristic is foundational to how these funds operate. When an investor wants to sell their shares, they can do so by redeeming them back to the fund. The price at which the shares are redeemed is calculated based on the net asset value (NAV) of the fund, which is typically determined at the end of each trading day. This liquidity is a key attraction for investors, as they have the flexibility to enter and exit their investment positions without significant restrictions.

In contrast, the other choices highlight aspects that do not align with the nature of open-end investment companies. For instance, they do not issue shares only through an IPO process, as they can continuously create and issue new shares to accommodate demand. Additionally, open-end funds do not maintain a fixed number of shares; instead, the number of shares can fluctuate based on investor demand. The ability to convert between share classes exists, but it is not a defining characteristic of open-end companies in the same way that redeemability is.