In a booming stock market, the ETF industry is seeing explosive growth piling up huge assets in recent years. This has resulted in enough liquidity in the ETF world with most of the funds trading at extremely higher volumes.Volume can be determined by the number of shares traded in a particular period. A higher number of shares provides easy access to move in and out of a product, keeping the bid/ask spreads tight.In fact, greater volume ensures easy creation and redemption of shares in the fund basket, which is a regular and vital mechanism in ETFs. This is especially true as authorized participants (AP) have the ability to create new baskets of ETF shares for underlying securities or redeem them when required. This phenomenon allows ETFs to trade in line with their net asset value (NAV).That said, we have highlighted 10 ETFs that have seen higher average volumes over the past three months and are thus the top 10 funds by trading volume, per etfdb.com (see: all the Category ETFs here). SPDR S&P 500 ETF SPY – Average Daily Volume: 74.3 million sharesThis fund tracks the S&P 500 Index and holds 505 stocks in its basket with information technology, healthcare, consumer discretionary, financials and communication services being the top five, with a double-digit allocation each. The ETF charges investors 9 bps in annual fees and has a Zacks ETF Rank #2 (Buy) with a Medium risk outlook (read: Top-Ranked ETFs to Buy as S&P 500 Nears Record High).ProShares UltraPro Short QQQ SQQQ – Average Daily Volume: 74.2 million shares This ETF provides three times (300% or 3X) inverse exposure to the daily performance of the Nasdaq-100 Index, charging 95 bps in annual fees. It has AUM of $1.9 billion.Financial Select Sector SPDR Fund XLF – Average Daily Volume: 53.5 million sharesThis is the ultra-popular financial ETF with AUM of $42.2 billion. It seeks to provide exposure to 65 companies in the diversified financial services, insurance, banks, capital markets, mortgage real estate investment trusts, consumer finance, and thrifts and mortgage finance industries. The product charges 12 bps in annual fees and has a Zacks ETF Rank #1 (Strong Buy) with a Medium risk outlook (read: Record Inflows to U.S. ETFs This Year: 6 Winners).Invesco QQQ QQQ – Average Daily Volume: 43.4 million sharesThis product provides exposure to the 102 largest domestic and international companies, excluding financial stocks, by tracking the Nasdaq-100 Index. It has AUM of $169.6 billion and charges 20 bps in annual fees. Information technology takes the largest share at 489.4% while communication services and consumer discretionary round off the next two spots. The fund has a Zacks ETF Rank #2 with a Medium risk outlook.iShares MSCI Emerging Markets ETF EEM – Average Daily Volume: 37.9 million sharesThis fund offers exposure to large and mid-sized companies in emerging markets. It follows the MSCI Emerging Markets Index and holds 1,232 securities. Among the emerging countries, China takes the top spot at 40% while Taiwan and South Korea round off the next two spots with a double-digit exposure each. The fund has AUM of $32.3 billion and charges 70 bps in annual fees. It has a Zacks ETF Rank #4 (Sell) with a Medium risk outlook.ProShares UltraPro QQQ TQQQ – Average Daily Volume: 34.2 million sharesThis is the most-popular ETF in the leveraged space with AUM of $11.6 billion and expense ratio of 0.95%. The fund seeks to deliver three times the return of the daily performance of the NASDAQ-100 Index.Energy Select Sector SPDR XLE – Average Daily Volume: 30.4 million sharesThis is the largest and most-popular ETF in the energy space with AUM of $24.4 billion and expense ratio of 0.12%. The fund follows the Energy Select Sector Index and holds 22 securities in its basket. It has a Zacks ETF Rank #2 with a High risk outlook (read: Can Energy Stocks & ETFs Continue Their Hot Streak?)iShares MSCI Brazil ETF EWZ – Average Daily Volume: 30 million sharesThis fund targets the Brazilian stock market and follows the MSCI Brazil 25/50 Index. Holding 54 stocks in the basket, financials and materials dominate the fund’s return at 25% each, followed by energy (12.3%) and consumer staples (10.5%). The fund has amassed $6.7 billion in its asset base and charges 59 bps in fees per year from investors. It has a Zacks ETF Rank #5 (Strong Sell) with a High risk outlook.iShares Russell 2000 ETF IWM – Average Daily Volume: 27.8 million sharesIt is one of the largest and the most-popular ETFs in the small-cap space with AUM of $68.7 billion. It tracks the Russell 2000 Index and holds 2,038 stocks in its basket with key holdings in healthcare, financials, industrials, consumer discretionary and information technology. The fund charges 19 bps in annual fees and has a Zacks ETF Rank #3 (Hold) with a Medium risk outlook (read: Fed Rate Hike in the Cards? ETFs to Buy).iShares Silver Trust SLV – Average Daily Volume: 24.4 million sharesThe fund offers exposure to the day-to-day movement of the price of silver bullion. It is an ultra-popular silver ETF with AUM of $15.1 billion and charges 50 bps in fees per year from investors. SLV has a Zacks ETF Rank #3 (Hold) with a High risk outlook.Want key ETF info delivered straight to your inbox?Zacks’ free Fund Newsletter will brief you on top news and analysis, as well as top-performing ETFs, each week. Get it free >>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Invesco QQQ (QQQ): ETF Research Reports SPDR S&P 500 ETF (SPY): ETF Research Reports Energy Select Sector SPDR ETF (XLE): ETF Research Reports Financial Select Sector SPDR ETF (XLF): ETF Research Reports iShares MSCI Emerging Markets ETF (EEM): ETF Research Reports iShares Russell 2000 ETF (IWM): ETF Research Reports iShares Silver Trust (SLV): ETF Research Reports iShares MSCI Brazil ETF (EWZ): ETF Research Reports ProShares UltraPro QQQ (TQQQ): ETF Research Reports ProShares UltraPro Short QQQ (SQQQ): ETF Research Reports To read this article on Zacks.com click here. Zacks Investment Research Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report