On above average volume, the iShares Russell 200o ETF (NYSEArca: IWM) gained almost 1% Thursday to race to a fresh all-time high. The rub is that small-caps, which usually trade at higher valuations than their mid- and large-cap counterparts, are getting a tad rich in the valuation department.

When the Russell 2000 Index gets to 1,100, it will be trading at a price-to-earnings ratio of just above 18 for its 2013 forecasts, well above the long-term average of 14.9, reports Alexandra Scaggs for the Wall Street Journal, citing Bank of America Merrill Lynch.

BofA Merrill Lynch also noted most small-cap sectors, technology being the exception, are trading at valuations above their long-term averages. The bank pointed out that consumer discretionary and staples small-caps look pricey, the Journal reported.

The PowerShares S&P SmallCap Consumer Discretionary Portfolio (NasdaqGS: PSCD) and the PowerShares S&P SmallCap Consumer Staples Portfolio (NasdaqGS: PSCC) have an average P/E of 21.5, according to PoweShares data.

Only the PowerShares S&P SmallCap Utilities Portfolio (NasdaqGS: PSCU) has a P/E of 19 among the nine PowerShares small-cap sector ETFs.