Based on ETF asset flows you’d think patriotism was some sort of magical investment strategy. The two biggest ETFs, SPDR S&P 500 (SPY) and iShares Core S&P 500 ETF (IVV) have combined assets of more than $225 billion. The next two largest ETFs, the iShares MSCI EAFE (EFA) and the Vanguard FTSE Emerging Markets ETF (VWO) have a combined asset base of $100 billion. That near 70/30 split between U.S. and foreign stocks is a tad out of whack. The Vanguard Total World Stock ETF (VT), a market cap weighted global portfolio that includes developed and emerging markets has about 50% in the U.S.

Performance chasing is no doubt at play here.

SPY Total Return Price data by YCharts

Yes, Europe’s economies are back in stall mode. Japan had a rough second quarter as well. And China is still working its way through its massive debt migraine. But let’s remember that markets move ahead of economic data.

And underweighting international stocks is thumbing your nose at a pretty compelling valuation advantage. The Leuthold Group uses a 5-year normalized PE ratio that incorporates 4 ½ years of actual earnings and six months of forward estimates. Right now the MSCI USA index trades at a normalized PE ratio of around 23x while the MSCI World ex-U.S. is at 19.1. That 1.22 premium for the U.S. is down from the recent high of 1.52 in May 2012.

But 1.2x is still a significant enough premium to lead Leuthold’s Doug Ramsey to opine that, “The United States’ large P/E premium relative to the rest of the world suggests that “foreign equities should produce total returns of about two percentage points (annualized) above the U.S. over a seven to ten-year horizon.”

A peek at YCharts recently expanded ETF coverage helps drive home the valuation point. Call up a quote and scan over to the right side of the page to find the Fundamentals section.

The SPDR S&P 500 trades at a forward PE ratio of nearly 17, its prospective price-to-sales ratio is 1.7x and price-to-book value ratio is 2.3.

Next, fire up the quote for the iShares MSCI EAFE ETF, which tracks an index of developed country stocks ex-US. The forward PE ratio is 15.2, price-to-sales is below 1.0 and price to book is 1.5x.

Same story in developing markets: The Vanguard Emerging Markets ETF has a prospective PE of 12.5x, price-to-sales is 1.2x and price to book clocks in at 1.6x.

Looking for some income ballast? Based on trailing actual dividend payments, the income payouts are equally unimpressive for all three portfolios.

SPY Dividend Yield (TTM) data by YCharts

But if you switch your gaze over to prospective yield -- also available on the main quote page in the same Fundamentals section, the two international ETFs have forecasted dividend yields that are more than 50 basis points above the anticipated payout for the S&P 500.

Carla Fried, a senior contributing editor at ycharts.com, has covered investing for more than 25 years. Her work appears in The New York Times, Bloomberg.com and Money Magazine. She can be reached at editor@ycharts.com. Read the RIABiz profile of YCharts. You can also request a demonstration of YCharts Platinum.