Bonds for the long run? Super-safe Treasurys are crushing the S&P

10-year Treasury hits all-time low

Forget stocks — how about bonds for the long run?

Over the past 10 years, one would have been better off keeping their money in a bond product rather than in a broad equity ETF. Specifically, the popular Barclays long-term Treasury bond ETF (TLT) has risen 71 percent over the past decade, while the SPDR S&P 500 ETF (SPY) is up 64 percent.

Since the TLT generally throws off a higher dividend yield, the performance comparison including reinvested dividends is even more dramatic: The SPY has generated a one-decade compound total return of 102 percent, but the TLT has returned an additional 40 percent on one's initial investment.

While doubling one's money is nothing to sneeze at, it is striking that one could have done so much better in ultra-safe bonds. Government bonds are stereotypically considered the bowling lane bumpers of the investment world — the pick for those uninspired investors who, rightly or wrongly, favor safety over all else (where "else" is generally taken to mean "more money").

Yet as bond yields have staged a massive slide culminating, for now, in Tuesday's all-time low of 1.357 percent on the 10-year Treasury note, bond performance has been downright extraordinary. From the modern vista, buying bonds a decade ago, when the 10-year note yielded some 5 percent per year, looks like the trade of a lifetime.

This is especially the case given that stock market volatility has been significantly higher than bond market volatility since then, meaning that the reward-per-risk trade-off has been deeply superior in Treasurys.

At this juncture, opinions remain sharply divided over which asset class will perform best over the years to come.

For Eddy Elfenbein, editor of the Crossing Wall Street blog, the fact that the S&P's dividend yield of about 2.2 percent is far greater than the 10-year yield points the way to investing in equities.

"The math says stick with stocks," he said Tuesday on CNBC's "Power Lunch. "

The issue is that the S&P dividend yield has generally been higher than the 10-year yield since August, and yet the TLT has outperformed the by more than 20 percent over the past year, and by 16 percent in 2016.

When he takes the long view on the 10-year yield, Chris Verrone, technical analyst at Strategas Research Partners, notes that "we've seen people fighting this the entire way down. We heard at 3 percent that they'd never go lower, and we heard the same at 2 percent."

Yet with negative-yielding government bonds in Germany, Switzerland, Japan and other countries, "I think you circle 1.00 on your chart — that's where we think this is going," Verrone said Tuesday on CNBC.