Occasionally, issuers of exchange traded funds swap indices. The news, with a few exceptions, is rarely earth-shattering.

News of an ETF changing its index may not always be front page news, but it is still important to investors. Index changes among sector ETFs highlight the importance of knowing what is under the hood. For example, not all ETFs that have “technology” in their names are heavy on Apple (NasdaqGS: AAPL), Google (NasdaqGS: GOOG) and Microsoft (NasdaqGS: MSFT). [Small Index Variations Matter]

The PowerShares DWA Healthcare Momentum Portfolio (NYSEArca: PTH) is, in the short time since the change, proving to be a beneficiary of a recent index swap. Last week, 10 PowerShares ETFs transitioned to Dorsey Wright indices, which focus on identifying stocks with impressive relative strength. PTH was one of those ETFs. [PowerShares ETFs Changes Indices]

As a health care ETF, PTH did not need a lot of help. From the start of 2014 through Feb. 18, its last day with its old index, PTH gained 7.2%. [Health Care ETFs Leading the Way]

If biotechnology stocks keep behaving as they have been, investors in PTH will be glad PowerShares made the index swap. At the end of 2013, PTH had a biotech weight of 13.9%. Now that it tracks the DWA Healthcare Technical Leaders Index, the ETF’s biotech weight has nearly tripled to 39.9%.