RVT) and BlackRock Credit Allocation Income Trust IV ( BTZ) offer discounts of as high as 16%. The discount is the gap between the funds' price and their net asset value -- the worth of the underlying assets. If the difference between the two disappears, investors pocket the difference. Closed-end funds are popular for investors chasing high yields, especially during times of low interest rates like today. For instance, Bill Gross has managed the Pimco High Income ( PHK), which has a distribution rate of 11%. Maury Fertig, chief investment officer at Relative Value Partners, a registered investment adviser in Northbrook, Ill., with more than $500 million in assets, says several closed-end funds sport attractive yields, though it's now getting harder to identify bargains. As the Federal Reserve earlier this month stated its intention to keep rates low, investors were given an incentive to seek out fatter yields and dividends. "The real desire for yield in the last few years has pushed the average bond fund up to net asset value," Fertig says. "The bargains were there for a long time, but they've gone away. There are still a few equity funds that are most interesting. The biggest values remain in the equity world." Relative Value Partners' niche is closed-end funds and exchange traded funds. Often the best opportunities are found when looking at the discount to the net asset value of a fund, or NAV. Fertig's first goal is to help investors understand the benefit of closed-end funds. Rather than chasing the higher yields, he wants investors to understand that they have to go to the secondary market to buy and sell shares of the fund, so the manager doesn't have to deal with redemptions. Second, managers can goose the returns of a fund because they are able to employ leverage. The yield curve is so steep, Fertig says, that the cost of borrowing is cheap. That may work in a stable or improving market, although it proved to be an unwise move during the collapse in late 2008 and early 2009. Fertig's most important lesson, though, is for investors to understand that the best closed-end fund bargains are to be had when they are priced lower than their historic discounts. That means avoiding funds trading at a premium, like the Pimco High Income Fund, he says. "You're paying $1.40 for $1 in assets," he says. "People will see Pimco High Income yielding 11% without knowing it's trading at a premium. This has an NAV of $9 and it trades at $13. The risk is that all of a sudden, something precipitates retail selling of the high-yield market. You don't have a safety net." Instead, Fertig examines funds that have broken down for one reason or another by comparing the market price to the net asset value. "We look for places where we think will be an opportunity or catalyst that will get rid of that discount," he says. "That's the principle reason we play in closed-end funds." To narrow the search for value more, investors should look at the historical returns of the NAV. When a return to the norm is expected, value is found, Fertig says. This investment theme is not without risks. Fertig says the biggest risk is buying a fund with a great discount without looking at the underlying assets. "It's possible to have some bad assets or the underlying fees are insane," he says. Read on to see three closed-end funds Fertig recommends to investors that are trading at an above-average discount to net asset value on a historical basis.