Investors should be careful not to stretch for yield in the current low-rate environment. A multi-asset income strategy mixing yield, defense and growth is a much smarter - and safer - way to go, said Scott Wolle, CIO for the Invesco Global Asset Allocation team (IVZ) - Get Report . Investors face difficult challenges when it comes to income with yields near historic lows even for assets that have traditionally had attractive yields like high yield bonds and emerging debt. As investors step farther out onto the risk spectrum, whether by accepting lower quality or longer duration, they are more exposed to capital losses. Many assets that currently have reasonable yields have experienced peak-to-trough losses of up to 50% or more, according to Wolle. Wolle finds it hard to see investors "doing well" in high yield bonds from here on in. The SPDR Barclays High Yield Bond ETF (JNK), for example, is up 13% year-to-date and yields only 6%. In his view, the risk/return ratio when yields are that low is simply "not worth it" on a stand-alone basis. Similarly, Wolle said REITs are having a great year, but valuations are now on the high end, while yields are on the low end. The price risk, in his view, is "awfully high." And the same goes for emerging market bonds, which have had a great run after being shunned by investors not too long ago.