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 Expanded Tech Sector ETF (NYSE:IGM)

IGM is up 2.68% over the trailing week.

The iShares Expanded Tech Sector ETF offers exposure to the U.S. tech market. It is a relatively low-cost option and extremely liquid.

The fund has $3.15 billion in AUM and an expense ratio of 0.41%. IGM has holdings in 280 companies, with the 10 largest comprising 54.72% of the fund.

The fund's largest holdings are Alphabet Inc. Class A (NASDAQ:GOOGL) and Apple Inc. (NASDAQ:AAPL) making up 8.83% and 8.68% of the fund, respectively.

IGM is up 40.52% YTD.

iShares Russell Top 200 Growth ETF (NYSE:IWY)

IWY is up 2.34% 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 $6.53 billion in AUM and an expense ratio of 0.20%. The fund has holdings in 112 companies, with the 10 largest comprising 59.90% of the fund.

The fund's largest holdings are Apple Inc (NASDAQ:AAPL) and Microsoft Corporation (NASDAQ:MSFT) making up 14.23% and 13.08% of the fund, respectively.

IWY is up 31.33% YTD.

Losers

Vanguard Extended Duration Treasury ETF (NYSE:EDV)

EDV is down 6.17% over the trailing week.

The Vanguard Extended Duration Treasury ETF provides exposure to long-dated US treasuries. The maturity dates range from 20 to 30 years.

The fund has $2.15 billion in AUM and an expense ratio of .06%.

EDV is down 19.40% YTD.

VanEck Oil Services ETF (NYSE:OIH)

OIH is down 5.78% over the trailing week.

The VanEck Oil Services ETF tracks the 25 largest US-listed Oil companies involved in the exploration, drilling, and refining of oil. Some of the equities, about a quarter, are foreign companies listed in both their local exchanges and a US exchange.

The fund has $2.34 billion in AUM and an expense ratio of 0.35%. OIH has holdings in 26 companies, with the 10 largest comprising 72.94% of the fund.

The fund's largest holdings are Schlumberger N.V. (NYSE:SLB) and Halliburton Company (NYSE:HAL) making up 19.99% and 11.52% of the fund, respectively.

OIH is up 6.92% YTD.