Well before the Fed began priming the liquidity pump in 2008, bonds had already been enjoying a remarkable bull run. So it’s hard to predict how interest rates and bond prices will respond to the changing economic environment. “We’ve been in a bond bull market for so long that we have little recent history to go on,” says Whitebox Advisors’ Wiley.

Frankly, it’s unclear how such factors will play out. But there is a growing consensus that investors need to broaden their exposure to assets outside of the traditional bond/stock axis and toward what’s known as alternative investments.

Few are calling for a complete withdrawal from stocks and bonds, but Michael Underhill, co-founder of Capital Innovations, notes that major investment offices at Harvard, Yale and elsewhere now hold 20% to 25% of their portfolios in alternative investments.

Underhill wrote The Handbook of Infrastructure Investing in 2010, and today guides a fund run by his firm called the Capital Innovations Global Agri, Timber, Infrastructure Fund (INNAX). He’s a fan of “real assets” and has added niches such as toll road operators to his purview.

In search of other alternative investments? Well, a range of options exist. Many were once only accessible to hedge fund managers with billions in assets under management. But the choices are widening, making them more accessible to financial advisors and retail investors.

Whitebox’s Wiley says his firm tends to seek out investments that will hold up during a rising rate environment. A good chunk of the Whitebox Tactical Advantage Investor fund (WBIVX) is currently focused on the highest-quality end of the high-yield bond market (the “BB’s”) and the fund pairs those holdings with a hedging short position in short-dated U.S. Treasurys. Wiley is also a fan of bank debt. “They are floating-rate by nature, so their coupons will adjust upward if rates rise,” he says.

Morton Capital’s Sarti is gravitating toward less liquid investments these days. “Traditional assets such as bonds are becoming very expensive,” he says. He thinks “investors are paying up for liquidity in part because liquid assets have done extremely well in recent years.” As a result, less liquid assets appear to offer better relative value these days.

One area of focus: private lending. “Banks have retrenched from traditional lending, and a void has been created,” says Sarti. Other illiquid assets his firm currently favors are real estate equity, oil and gas partnerships and health-care royalties.

That last category is the kind of investment that offers long-term returns uncorrelated to public market benchmarks. In a nutshell, investment firms such as Morton Capital, through intermediary funds, provide financing to biotech firms, universities and drug inventors in exchange for a slice of future cash flows once products hit the market. “It’s helpful to biotech firms that still have funding needs, can’t tap bond markets and don’t want to dilute existing shareholders,” says Sarti.

Another asset class with virtually no correlation to stocks and traditional bonds is “catastrophe bonds.” These are issued by reinsurance companies that need to shore up their own capital bases after major insurable events such as hurricanes, earthquakes and other “acts of God.” Because these bonds address different types of events in multiple regions, they tend to make great diversification tools, even within the same asset class.

Of course, the most popular way to gain alternative investment exposure is through liquid alternative investment mutual funds. These follow traditional hedge fund strategies and provide the added benefits of liquidity and transparency while avoiding the deep asset concentration that some hedge fund managers tend to pursue.

Trouble is, it can be hard to know where to start. Morningstar tracks more than 600 liquid alternative funds spread among 15 subcategories. When investors look only at those pursuing hedge fund-style alternative strategies, the field is narrowed to around 325 funds, Goldman Sachs Asset Management has noted.