We performed a screening of mid-cap ETFs, defined as having Assets Under Management (AUM) between $2 billion and $10 billion – to determine what funds had the largest positive and negative returns on the week, according to data from etfdb.com. Only non-leveraged funds were considered.

Winners

iShares Russell Top 200 Growth ETF (NYSE:IWY)

IWY added $526.63 million in AUM over the trailing week.

The iShares Russell Top 200 Growth ETF tracks the Russell Top 200 Growth Index, offering exposure to large-cap companies within the growth sector of the U.S. equity market. 

IWY has $7.36 billion in AUM and an expense ratio of 0.20%. The fund has holdings in 112 companies, with the 10 largest comprising 59.65% of the fund.

The fund's largest holdings are Apple Inc (NASDAQ:AAPL) and Microsoft Corporation (NASDAQ:MSFT) making up 14.22% and 13.39% of the fund, respectively.

IWY added $1.33 billion in net assets, YTD.

iShares MSCI Emerging Markets ex China ETF (NYSE:EMXC)

EMXC added $308.32 million in AUM over the trailing week.

The iShares MSCI Emerging Markets ex China ETF offers exposure to companies from emerging markets around the world while excluding Chinese equities. For investors wary of China's economic outlook, this offers an attractive opportunity.

The fund has $4.95 billion in AUM and an expense ratio of 0.25%. EMXC has holdings in 1000 companies, with the 10 largest comprising 30.04% of the fund.

The fund's largest holdings are Taiwan Semiconductor Manufacturing Co., Ltd. (TPE: 2330) and Samsung Electronics Co., Ltd. (KRX: 005930) making up 9.04% and 5.19% of the fund, respectively.

EMXC added $2.62 billion in AUM, YTD.

Losers

iShares Expanded Tech-Software Sector ETF (BATS:IGV)

IGV lost $390.00 million in net assets over the trailing week.

The iShares Expanded Tech-Software Sector ETF invests in US-based tech companies. Although it does offer exposure to tech behemoths that dominate most tech-focused ETFs, much of the fund is weighted to lesser-known medium-cap companies.

IGV has $6.85 billion in AUM and an expense ratio of 0.41%. The fund has holdings in 117 companies, with the 10 largest comprising 59.69% of the fund.

The fund's largest holdings are Microsoft Corporation (NASDAQ:MSFT) and Adobe Incorporated (NASDAQ:ADBE) making up 9.19% and 9.07% of the fund, respectively. IGV lost $55.30 million in net assets YTD.

SPDR Portfolio Short Term Treasury ETF (NYSE:SPTS)

SPTS lost $317.84 million in net assets over the trailing week.

The SPDR Portfolio Short-Term Treasury ETF tracks an index of US Treasuries dated 1 to 3 years.

SPTS has $51.48 billion in AUM and an expense ratio of 0.03%. 

SPTS added $5.33 billion in net assets YTD.