Nuveen Municipal Income Fund Inc. (NMI)

Nuveen Municipal Income Fund is a fund that buys municipal bonds — the debt that cities and states issue to pay for roads, schools, water systems, and other infrastructure. Instead of buying these bonds yourself, you buy shares of this fund, and the fund uses your money to hold a big basket of municipal bonds. When the cities and states pay interest on their bonds, the fund collects that interest and pays most of it back to you, its shareholder. It is a simple idea: pool money from many investors to buy a diversified collection of bonds, collect the interest, and pass it through.

How the fund works

When you buy a share of Nuveen Municipal Income Fund, you own a tiny piece of a large portfolio of municipal bonds. The fund’s managers buy bonds issued by states and cities. These bonds are debt — cities and states borrow money by issuing bonds, and they pay back the money with interest. New York might issue a bond to build a subway extension. California might issue one to pay for schools. A city might issue one to fix its water pipes.

The fund collects interest payments from all these bonds and distributes most of the money to shareholders like you. If you own 100 shares and the fund collects $10,000 in interest, you might get paid $50 — your share of the total.

The magic is the tax advantage. Here is the key: interest you earn on municipal bonds is usually not taxed by the federal government. If you hold a regular bond and earn $1,000 in interest, you pay federal income tax on that $1,000. If you hold a municipal bond and earn $1,000 in interest, you typically owe nothing to the federal government. That is a huge advantage for people in high tax brackets.

This is why the fund exists. Wealthy investors want to earn income from bonds but hate paying federal tax on it. Municipal bonds offer a way to earn income with less tax. A fund like this lets you buy many municipal bonds at once, so you are diversified (if one city has trouble paying its bond, you still have payments from dozens of others).

Closed-end fund versus open-end fund

Nuveen Municipal Income Fund is a closed-end fund. That means it has a fixed number of shares that were issued when the fund launched. There are no new shares being created. If you want to own the fund, you buy existing shares from someone else on the stock exchange, just like buying a stock.

This is different from a regular mutual fund, which is open-end. With an open-end fund, the company creates new shares whenever someone wants to buy in, and destroys shares when someone wants to sell. The price of an open-end fund is always tied to its actual holdings.

A closed-end fund works differently. The price of a closed-end fund’s shares is set by supply and demand on the stock exchange. The fund might hold bonds worth $10 per share, but the shares might trade for $9.50 or $10.50, depending on whether investors want to buy or sell. That difference — between what the bonds are actually worth (net asset value) and what people will pay for the shares — matters. If the fund trades at a discount (cheaper than the bonds are worth), it is a good deal. If it trades at a premium (more expensive), you are paying extra.

What could go wrong

Municipal bonds are generally safe — states and cities have lower default rates than corporations. But they are not risk-free.

Credit risk: A city or state could run out of money and fail to pay its bond. This is rare but has happened. Detroit went through bankruptcy in 2013. Some cities and states are running chronic deficits. If a big issuer fails, the fund’s interest income drops and its share price falls.

Interest rate risk: If interest rates go up, existing bonds become less valuable. You hold a bond paying 3% interest, but new bonds are paying 5%. Your bond is worth less because no one wants to buy a 3% bond when they can get 5% elsewhere. If the fund has to sell bonds before they mature (paying back all the money), it may have to sell at a loss.

Reinvestment risk: The fund collects interest and distributes it to you. But what happens to that money? If you spend it, you are fine. If you reinvest it into new bonds or fund shares, you might have to do so when interest rates are lower, earning less income.

Liquidity risk: Municipal bonds are not always easy to trade quickly. If the fund needs to raise cash quickly, it might have trouble selling bonds without taking a loss.

Tax risk: Congress could change the law about municipal bond taxation. If interest on municipal bonds suddenly became taxable, the appeal of these bonds would collapse and their prices would fall.

The portfolio and diversification

Nuveen Municipal Income Fund holds hundreds of municipal bonds across many states and cities. The fund manager decides which bonds to buy. A well-managed fund will have some variety: bonds from strong cities that are unlikely to default, bonds from weaker cities that pay higher interest (riskier but better income), short-term bonds and long-term bonds.

The fund publishes its holdings regularly, so you can see exactly which bonds it owns. If you want to know whether the fund is taking on too much risk or too little, look at the bonds it holds.

Why the fund matters to investors

Nuveen Municipal Income Fund is one way for investors to get diversified exposure to municipal bonds and collect federal-tax-free income. There are alternatives: you could buy municipal bonds yourself, or you could buy an open-end municipal bond mutual fund. But this fund has been around for decades, attracts a lot of money, and has a professional manager.

For someone in a high tax bracket who lives in a state with high state income taxes, municipal bonds are genuinely valuable because the income is not taxed by the federal government (and often not by the state either, if you buy bonds from your own state). A fund makes this accessible without having to pick individual bonds yourself.

The downside is that you trust the fund manager to pick good bonds. If the manager makes bad picks or if something unexpected happens in the municipal bond market, the share price can fall. And because it is a closed-end fund, you are subject to the whims of supply and demand on the stock exchange. Buy at the wrong time and you might pay a premium; sell at the wrong time and you might take a discount.

How to research Nuveen Municipal Income Fund

Start by looking at the fund’s annual report and fact sheet. These tell you what bonds the fund holds, what percentage of the fund is in different types of bonds, how much the bonds are worth, and what the fund is charging you in fees.

Look at the fund’s discount or premium. Is it trading at a discount (good) or premium (bad)? Has this changed over time? A fund that trades at a big premium is being overpaid by the market.

Check the fund’s yield — how much income it is paying out relative to the share price. Compare this to other municipal bond funds. Also look at the fund’s history: have the payments been steady, or have they fluctuated a lot? Stable payments are better.

Finally, look at the bonds in the portfolio. Are they mostly from strong states and cities, or is the fund taking on more risk to chase higher income? A fund that is taking too much credit risk might be unsustainable.

For any investor considering this fund, understand what you own: a basket of municipal bonds held by a professional manager, paying you the interest those bonds generate, with the benefit of federal tax exemption. The fund is only as good as the bonds it holds and as stable as the cities and states that issued them.