Small-cap stocks and small-cap ETFs often outperform their large-cap counterparts over the long-term with the trade off being that smaller stocks are usually more volatile than their large-cap peers.One of the primary reasons small-cap stocks outpace their larger peers is the markets often assign higher growth expectations to smaller companies. It is simple math. A small-cap stock with a market value of, say, $1 billion can more easily double or triple in size than a company with a current market capitalization of $50 billion or $100 billion.So in theory it would be reasonable to expect that the combination of small-cap stocks and the growth factor would be rewarding for investors. It can be…over the right time horizons, but historical data indicate small-cap growth often lags small-cap value. However, the bull market is raging on and that has been a boon for growth fare, including plenty of small-cap stocks and ETFs.InvestorPlace - Stock Market News, Stock Advice & Trading TipsWhat has recently been vexing about small-cap stocks is the laggard status of growth in this category. With large- and mid-cap growth funds and stocks setting a torrid pace in the first quarter, small-cap growth was left behind. Small-cap growth funds were among the worst-performing style funds in the first three months of the year. * 7 Tech Stocks With Too Much Risk, Not Enough Upside For risk-tolerant investors seeking exposure to small-cap ETFs, here are some growth funds to consider. SPDR S&P 600 Small Cap Growth ETF (SLYG)Source: Shutterstock Expense ratio: 0.15% per year, or $15 on a $10,000 investment.The SPDR S&P 600 Small Cap Growth ETF (NYSEARCA:SLYG) is a basic approach to small-cap stocks dwelling in the growth space. SLYG, which tracks the S&P 600 SmallCap Growth Index, is also one of the more highly related small-cap growth funds by some industry observers, though that is not saying much as many analysts are mostly tepid on this fund style.SLYG's underlying index "includes stocks that exhibit the strongest growth characteristics based on: sales growth; earnings change to price; and momentum," according to State Street. The result is a portfolio of 335 small-cap stocks with a weighted average market value of $2.07 billion.SLYG allocates nearly 36% of its combined weight to industrial and healthcare small-cap stocks and another 29% to the financial services and technology sectors. While 2019 is not even a third of the way over, SLYG's year-to-date gain of 13.50% is endemic of small-cap growth's laggard ways against small-cap value. The SPDR S&P Small Cap Value ETF (NYSEARCA:SLYV), SLYG's value counterpart, is up 17.20% this year. Invesco S&P SmallCap 600 Pure Growth ETF (RZG)Source: Shutterstock Expense ratio: 0.35%The name of the Invesco S&P SmallCap 600 Pure Growth ETF (NYSEARCA:RZG) makes this fund sound a lot like the aforementioned SLYG, but these are two different products and their index methodologies confirm as much.RZG tracks the S&P SmallCap 600 Pure Growth Index, which measures growth "by the following risk factors: sales growth, earnings change to price and momentum," according to Invesco. * 3 Stocks on Shaky Ground Assigning purity to growth gives RZG a roster of 147 stocks with an average market value of $1.58 billion, numbers that are materially different than SLYG. However, purity with small-cap stocks and the growth factor is not always a guarantee of stout returns. This year, RZG's value counterpart is beating the growth fund by 760 basis points. Vanguard Russell 2000 Growth ETF (VTWG)Source: Shutterstock Expense ratio: 0.20%As its name implies, the Vanguard Russell 2000 Growth ETF (NASDAQ:VTWG) is a collection of small-cap stocks from the Russell 2000 Growth Index, which is the growth offshoot of the popular Russell 2000 Index. To give investors an idea of how many small-cap stocks are classified as growth names, VTWG is home to 1,251 small-cap stocks.While small-cap stocks, growth, value and otherwise, are generally defined as those companies with market values of no more than $2 billion, different index providers use varying methodologies, which leading significant performance differentials. The aforementioned SLYG and RZG track indexes from Standard & Poor's while FTSE Russell issues VTWG's underlying benchmark.This is notable because VTWG is one of this year's best-performing small-cap growth ETFs. Importantly, VTWG is one of the few small-cap growth ETFs that is beating its value counterpart. Up 19.90% year-to-date, VTWG is topping the equivalent Vanguard small-cap value ETF by 400 basis points. VTWG allocates 44.40% of its combined weight to the healthcare and consumer discretionary sectors. iShares Morningstar Small-Cap Growth ETF (JKK)Source: Shutterstock Expense ratio: 0.30%As was just noted with VTWG, an ETF's underlying index matters. The iShares Morningstar Small-Cap Growth ETF (NYSEARCA:JKK) tracks the Morningstar Small Growth Index and there must be something in that water because JKK is up 22.30% this year, easily good for one of the best showings among small-cap growth funds.This year, JKK has been more volatile than some rival small-cap growth funds, but its three-year standard deviation of 16.16% is actually slightly lower than the comparable metric on the Russell 2000 Growth Index. * 7 Healthy Dividend Stocks to Buy for Extra Stability JKK allocates about 44.60% of its combined weight to the healthcare and technology sectors. Combining small-cap stocks from those sectors is common among growth funds, but there is something to consider with those sector allocations. Small-cap stocks in the healthcare and technology sectors frequently sacrifice cash flow generation and profitability to grow revenue. Some even take on debt to bolster growth, meaning there some small-cap stocks with the growth designation that are not as financially sturdy as some investors would like those companies to be. Invesco Russell 2000 Pure Growth ETF (PXSG)Source: Shutterstock Expense ratio: 0.39%The Invesco Russell 2000 Pure Growth ETF (NYSEARCA:PXSG) is another example of an ETF that assembles small-cap stocks with the growth label while adding a layer of growth purity. PXSG's methodology is working this year as the fund is up 18.28%, an advantage of about 410 basis points over its value rival.The growth purity qualifier is significant because PXSG holds just 301 stocks, or less than a quarter of the amount found in VTWG, which like PXSG tracks a Russell index. PXSG devotes over 44% of its weight to small-cap stocks that are healthcare or technology names.This fund highlights some of the aforementioned risks associated with small-cap stocks from those sectors. PXSG has a negative return on equity and investors will pay up for that privilege with a price-to-earnings ratio north of 57x. iShares Micro-Cap ETF (IWC)Source: Shutterstock Expense ratio: 0.60%Micro caps are different than small-cap stocks. The former typically have market values below the $200 million to $250 million that is the beginning part of small-cap stock territory. Due to lack of analyst coverage and institutional participation in the micro-cap arena, stock picking here is difficult, but the iShares Micro-Cap ETF (NYSEARCA:IWC) is a solid idea for investor seeking some micro-cap exposure.This year, IWC up 13.30%, but that trails broader gauges of small-cap stocks. While the fund's three-year standard deviation is only moderately higher than broader small-cap stock funds, there are sector-level concentration concerns as healthcare and financial services names combine for almost half IWC's weight. * 7 Stocks That Can Outperform for Years Additionally, IWC's annual fee of 0.60% is higher than those found on standard small-cap growth ETFs due to some of the liquidity issues associated with micro-cap stocks, That said, IWC's earnings multiples imply micro caps are somewhat inexpensive relative to diversified gauges of small-cap stocks. Invesco S&P SmallCap Information Technology ETF (PSCT)Source: Hillary via FlickrExpense ratio: 0.29%The Invesco S&P SmallCap Information Technology ETF (NASDAQ:PSCT) is not a dedicated small-cap growth fund, but it is fairly close. PSCT holds 88 small-cap stocks, 52.49% of which are classified as growth stocks compared to a 19.82% weight to value stocks.As mentioned throughout this piece, there are risks associated with the combination of small-cap stocks and the technology sector. However, a point in favor of PSCT is the isolation of small-cap stocks and technology as represented by this fund has led to out-performance of many of the growth funds highlighted here. Over the past three years, PSCT has handily outperformed the Russell 2000 and S&P SmallCap 600 growth benchmarks.The strike against PSCT is not its performance against comparable small-cap peers. It is the fund's risk-adjusted returns against the large-cap Nasdaq-100 and S&P 500 Technology indexes. Against those benchmarks, PSCT does not compare favorably.Todd Shriber does not own any of the aforementioned securities.Compare Brokers The post 7 Small-Cap Growth ETFs For Adventurous Investors appeared first on InvestorPlace.