Recently, Barron’s published a thought-provoking op-ed which triumphantly declared that stocks have already bottomed, which might not be the positive catalyst for index funds, as you might think it is. After all, one of the key advantages of this broad-stroke investment strategy is to mitigate volatility. Through multiple bets via a benchmark indicator, investors are less likely to suffer catastrophic losses.

Among the central points of the aforementioned op-ed centered on inflation; namely, the trajectory of rising prices may have peaked, which would imply a relaxing of the Federal Reserve’s hawkish policy. That would be great for individual wagers, which if correct would likely draw better rewards than index funds to buy. But here’s the thing – no one really knows for sure what may transpire next. Even the confident Barron’s article left room for doubt. Therefore, index funds to buy remain incredibly relevant, if not more so right now.

SPDR S&P 500 ETF Trust (SPY)

A venerable name among index funds to buy, the SPDR S&P 500 ETF Trust (NYSEARCA:SPY) generally corresponds to the price and yield performance of the benchmark S&P 500. On a year-to-date basis, SPY dropped a little over 16% of equity value, almost exactly the same as the S&P. Notably, though, in the trailing month, the SPY exchange-traded fund gained 5.5%, reflecting a possible momentum shift.

Fundamentally, the SPDR S&P 500 ETF focuses mostly on U.S.-based blue chips. Its top three holdings are Apple (NASDAQ:AAPL), Microsoft (NASDAQ:MSFT) and Amazon (NASDAQ:AMZN). These stocks represent 6.84%, 5.39% and 2.5% of the SPY’s holdings, respectively. Sector-wise, the SPY mostly covers the technology sector with a 23.73% weighting, followed by healthcare and financial services at 15.24% and 13.85%, respectively. On a final note, the expense ratio for the SPY pings at 0.09%. This compares very favorably to the category average of 0.41%.

Invesco QQQ Trust (QQQ)

While the tech sector delivers the most innovative businesses to investors, it also features some of the highest-risk profiles in the market. Still, those with a patient outlook may want to consider the Invesco QQQ Trust (NASDAQ:QQQ). Per its prospectus, it generally corresponds to the price and yield performance of the Nasdaq 100 index. Since the start of this year, QQQ declined nearly 29%.

At the same time, QQQ gained nearly 3% in the trailing month, reflecting a rise in enthusiasm for growth-oriented investments. Still, individual names can be risky during this ambiguous environment, thereby making QQQ an ideal play among index funds to buy. Through the QQQ, you can gain balanced exposure to Apple, Microsoft and Amazon – its top three holdings. As well, you can acquire intriguing discounts such as Alphabet (NASDAQ:GOOG, NASDAQ:GOOGL) and Tesla (NASDAQ:TSLA).

Obviously, tech represents the lion’s share of QQQ’s weighting at 48.23%. However, it also involves communication services and consumer cyclicals at weightings of 15.25% and 14.14%, respectively. Finally, the Invesco tech ETF features an expense ratio of 0.20%, below the category average of 0.56%.

SPDR S&P MidCap 400 ETF (MDY)

While large caps usually offer the most stable investment opportunities among index funds to buy, they can also be boring. For those investors that want a little extra kick in their portfolio but without going purely speculative, the SPDR S&P MidCap 400 ETF (NYSEARCA:MDY) could be just right. Per the ETF’s prospectus, the MDY corresponds to the price and yield performance of the S&P MidCap 400.

Since the beginning of the year, MDY dropped 10.5% of market value, which is rather surprising. Ordinarily, you’d expect the more stable large-cap index funds to buy to outperform during market volatility. In the trailing month, MDY gained 9.5%, reflecting strong near-term momentum.

The ETF’s top three holdings are Steel Dynamics (NASDAQ:STLD), First Solar (NASDAQ:FSLR) and First Horizon (NYSE:FHN). Primarily, MDY’s weighting focuses on the industrials at 18.52%, followed by financial services and consumer cyclical at 15.54% and 14.26%, respectively. Finally, MDY features an expense ratio of 0.22%, slipping under the category average of 0.41%.

iShares Russell 2000 Growth ETF (IWO)

Investors can’t live on bread-and-butter investments alone but must venture out into the wilderness of high-growth opportunities on occasion. Fortunately, in this day and age, investors enjoy ample and diverse selections among index funds to buy. In particular, those that want to roll the dice a bit should check out the iShares Russell 2000 Growth ETF (NYSEARCA:IWO). Per its prospectus, the IWO fund tracks the investment results of the Russell 2000 Growth Index.

The aforementioned index measures the performance of small-cap stocks. Indeed, the top three holdings of IWO feature lesser-known enterprises: ShockWave Medical (NASDAQ:SWAV), Matador Resources (NYSE:MTDR) and Emcor Group (NYSE:EME).

Mostly, the iShares Russell 2000 targets the healthcare segment at a 21.81% weighting, followed by technology (20.72%) and industrials (17.35%). Geographically, the IWO is mostly geared toward U.S. companies with a 98% weighting. Finally, the IWO fund features an expense ratio of 0.23%, significantly below the category average of 0.56%.

Vanguard 500 Index Fund (VFIAX)

Although ETFs garnered much popularity as index funds to buy, traditional mutual funds deliver their own advantages. For instance, the latter offers a wider variety of offerings and investment strategies. As well, mutual funds often facilitate superior support services.

Regarding the Vanguard 500 Index Fund (MUTF:VFIAX), this investment tracks the S&P 500. Currently, the VFIAX fund dropped 16% YTD. However, in the trailing month, it’s up nearly 6%. The Vanguard 500’s top three funds are identical to the venerable SPY: Apple, Microsoft and Amazon. In terms of sector weighting, the VFIAX primarily targets tech (24.69%), followed by healthcare (14.16%) and financial services (12.96%).

Finally, the VFIAX features a net expense ratio of 0.14%, below the category average of 0.87%. As well, its management fee is 0.13%, which sits below the category average of 0.5%.

Vanguard Emerging Markets (VEIEX)

Usually, financial advisors will direct their clients to U.S.-based investments. Owning the world’s reserve currency and (so far) the top economy brings with it incredible privileges. Still, the U.S. is a mature market. For those seeking more robust upside – in exchange for a higher-risk profile – the Vanguard Emerging Markets (MUTF:VEIEX) may be an intriguing alternative.

Per the fund’s prospectus, VEIEX closely tracks the MSCI Emerging Market Index. Since the start of the year, the fund lost over 22% of market value. However, in the trailing month, it gained over 9%, possibly reflecting a sentiment shift. Its top three holdings are Taiwan Semiconductor (NYSE:TSM), Tencent (OTCMKTS:TCEHY) and Alibaba (NYSE:BABA).

Currently, this Vanguard fund’s top weighting concentrates on financial services at 21.09%, followed by technology (15.87%) and consumer cyclical (13.76%). Finally, VEIEX features a net expense ratio of 0.29%, well below the category average of 1.26%. As well, its management fee is 0.27%, below the category average of 0.88%.

Vanguard S&P Small-Cap 600 (VSMSX)

While slow-and-steady investments in blue-chip enterprises may represent the surest way to wealth, it’s also time consuming. For those that want to quicken the pace in their index funds to buy, the Vanguard S&P Small-Cap 600 (MUTF:VSMSX) may provide an attractive alternative.

Since the January opener, VSMSX declined a bit over 12%, which again represents a relatively robust performance. In the trailing month, the mutual fund gained over 8%, demonstrating a return of bullish sentiment. According to its prospectus, the Vanguard S&P Small-Cap seeks to track the performance of the S&P SmallCap 600 index.

Presently, VSMSX’s top three holdings are Agree Realty (NYSE:ADC), ExlService (NASDAQ:EXLS) and Lantheus (NASDAQ:LNTH). Primarily, the fund targets the industrials sector with a 15.63% weighting, followed by tech (13.57%) and consumer cyclical (12.31%). Lastly, the VSMSX fund features a rock-bottom net expense ratio of 0.08%, well below the category average of 1.06%. Also, its management fee is 0.07%, below the category average of 0.69%.

On the date of publication, Josh Enomoto did not have (either directly or indirectly) any positions in the securities mentioned in this article. The opinions expressed in this article are those of the writer, subject to the InvestorPlace.com Publishing Guidelines.