For sure, who does not know sugar? Everyone use sugar . From the bottom to the top of the wealth pyramid. So, let's say sugar is our new world currency now, replacing USD. From the chart, you can see that just before the 2008 economic crisis, we spotted a decrease of SPX value relative to sugar for more than 2 years. Now, as we just recently reached ATH for US indices (in USD denomination), relative to Dow Jones UBS Commodity index, actually it looks more like a declining top (look at the 2 yellow boxes). So, it is not only for sugar , but also relative to this index.
So, back to the essence of stock valuation, what is actually a stock? It is part of ownership, given to the holder, with promise of earning payment, while in the event of bankruptcy, nothing left for the stockholder. Currently, valued in declining currency value relative to common commodity products, what would be next? Perhaps better to just hold the real things, which are for now. Not just a legal promise with declining fundamental valuation.
Additionally, Greenspan has called stagflation lately (http://www.bloomberg.com/news/articles/2016-07-28/greenspan-nervous-bond-prices-too-high-sees-stagflation-ahead). Perhaps, what he has seen is while commodity prices picking up, financial market values decreasing relative to common commodity prices, labor wages not picking up significantly with low GDP growth observed, this looks like going for stagflation.
Detailed explanation of DUBS: https://www.djindexes.com/mdsidx/downloads/fact_info/Dow_Jones-UBS_Commodity_Index_Fact_Sheet.pdf)
I tend to say that be careful with current market, but after looking at the latest evident on strong supports of SPX/DJI/DAX not broken yet, this week may be a game changer. We need to understand, there are 2 markets that investors worried about: stock and bond markets. If interest rate is to be hiked, the first to be left out will be bond market. In such event, stock market is the only option left for large institutional investors given bond pricing theory: long in duration with interest rate increase means catastrophe. We could see in the opposite of stock market going down, instead going up, along with other major commodities. Why? Because at the least you can expect stocks to pay dividends while commodities not.
So, while still cautious on the market at the moment, given what Lagarde has coined the term "new normal", SPX can reach 2200 and DJI can reach 20000 may be the new normal at current economic situation with cheap money.
Note the fib lines (may not be perfect)