A trader reacts at Frankfurt stock exchange January 29, 2014. REUTERS/Ralph Orlowski Goldman Sachs doesn't find stocks appealing anymore.

In a note Tuesday, the firm downgraded equities to "Neutral" over the next year.

"Until we see sustained earnings growth, equities do not look attractive, especially on a risk-adjusted basis," wrote Christian Mueller-Glissmann, an equity strategist.

"We expect particularly poor returns in dollar terms, with our forecast of a stronger dollar and the prospect of less negative equity/FX correlations."

It's virtually anything but stocks for Goldman; Mueller-Glissmann and team are "Overweight" cash on a three-month basis and think credit valuations are much better than stocks.

Bond yields have fallen amid reassurance from the Federal Reserve of slow interest-rate hikes and higher demand from foreign investors. The dollar has weakened, and commodity prices have gained.

That has lifted returns from credit and bonds but not for stocks.

And because Mueller-Glissmann expects the dollar to strengthen, he thinks equity returns in dollar terms are likely to be weak over the next year.

Other analysts are sounding the alarm for weak returns — and maybe losses — in the nearer term.

Last week, David Kostin, Goldman's chief US equity strategist, said that even though he expected a 3% rally by year-end, a shift in investor sentiment could easily trigger one more drop by up to 10% before that happens.

Like Mueller-Glissmann, Kostin noted that valuations look lofty. He also cautioned that a slower pace of corporate buybacks — which have been an important source of demand — and concerns surrounding the elections could raise the chances of another big sell-off.