When investment banks act as a market maker in the market for a high-yield bond, what service are they providing to institutional investors?

a. When an institutional investor wants to sell or buy, the IBs will go find another investor who wants to do the opposite, can usually find them within less than an hour, and will execute the trade with both sides and charge a commission.

b. The IBs help the institutional investor to raise funds to manage, e.g. from pensions, endowments and wealthy families

c. The IBs convinced the company to issue the high-yield bond, giving the institutional investors something to invest in.

d. The IBs provide liquidity / immediacy by quoting a bid price and offer price for the bond, allowing the investor to sell to or buy from the bank for immediate execution.