2. Canada and Australia. Even if one is quick to dismiss the emerging-market underperformance, how can one be quick to dismiss the strongest economies (at present) in the developed world? Australia and Canada are both projected to grow at a faster clip in 2012 than the U.S.; Canada and Australia both have a better employment situation. Nevertheless, the S&P SPDR Trust ( SPY) picked up 5.4% in five days, while iShares MSCI Australia ( EWA) logged a feeble 0.4% and iShares MSCI Canada ( EWC) registered a paltry 0.8%. This one can't even be blamed on faltering currencies, as the CurrencyShares Canadian Dollar ( FXC) gained roughly 1.5% on the dollar over the week. One might say that energy-rich Canada and materials-rich Australia are slumping due to a slowdown in the global growth story. Fair enough. Yet if that slowdown is real, it would hit U.S. equities sooner or later. Once more, without these healthier developed countries rallying, one would need to curb one's enthusiasm for the five-day U.S. phenomenon. 3. Commodities Still Faltering. This week was "risk on" for the U.S. alone. And while that may have a great deal to do with the dollar's gains, relief over Europe and/or perceived safety of U.S. multinationals, there's no ignoring global growth fears. PowerShares DB Base Metals ( DBB) was down 1.0% over the week. iPath DJ Copper ( JJC) lost 1.7%. PowerShares DB Agriculture ( DBA) lost 3.1%. Commodity stocks, which do not necessarily correlate with the underlying commodities and frequently correlate with the equity markets themselves, also struggled. Market Vectors Coal ( KOL) gave up 0.6%, Market Vectors Rare Earth Miners ( REMX) fell 1.1% and copper-heavy iShares MSCI Chile ( ECH) lost 4.3%. We can blame the dollar for some of the angst. Yet the evidence suggests that, even with sovereign debt band-aids, a return to bull market form will require foreign market participation. That is, without global economic growth showing definitive signs of improvement, U.S. stocks can only climb so far. You can listen to the ETF Expert Radio Show "LIVE", via podcast or on your iPod. You can follow me on Twitter @ETFexpert.