NEW YORK ( TheStreet) -- PowerShares WilderHill Progressive Energy (PUW) has led PowerShares WilderHill Clean Energy (PBW) by a wide margin over the past three months. PUW's return was 19.20% compared to only 0.76% for PBW.
Much of the gap between the ETFs came since the end of July, as PUW's return rose 12.2% while PBW rose 1.1%.
The stocks among PUW's top 10 holdings that provided the lift were Clean Fuels (CLNE - Get Report), up about 50%, along with Owens Corning (OC) and Chesapeake Energy (CHK - Get Report), up about 30%. Methanex (MEOH) also had a portfolio-outperforming return of just under 20%.
PBW's fund had similar returns from its top 10 holdings. Fuel Systems (FSYS) had return of nearly 50%, while Echelon (ELON) gained more than 50%. Cosan (CZZ) and International Rectifier (IRF) both gained more than 20%.On the downside, PUW's worst performing top 10 holdings were flat, while PBW saw Applied Materials (AMAT) and SunPower (SPWRA) lost ground. However, the current top 10 holdings don't tell the entire story. As of June 30, PBW's top 10 was dominated by solar stocks, including First Solar (FSLR - Get Report), Yingli (YGE), Evergreen (ESLR) and JA Solar (JASO). Over the aforementioned period, JASO lost 20%, FSLR lost nearly 15%, and ESLR lost more than 5%. Broadwind Energy (BWEN - Get Report), the former No. 1 holding on June 30, fell nearly 25% and went from 3.14% of PBW to 2.52% on Sept. 14. PUW has seen changes among its top 10 as well, but it more closely resembles its June 30 composition. A couple of stocks moved out of the top 10, including Southwestern Energy (SWN) and USEC (USU). However, these were more allocation changes than a price decline, as SWN was flat and USU actually gained 30% over the period. PowerShares ETFs have performed well in many cases, but investors need to pay attention to the holdings in these funds because they will shift over time -- and that will alter results. Since PUW's inception in October 2006 (PBW was launched in March 2005), the two funds have tracked very closely, with occasional under- and over-performance, until last fall. From its Nov. 19 low, PUW gained 105% compared to a 71% return for PBW.