What is a diversified portfolio?

A diversified portfolio is built from complementary assets, such as stocks and bonds, that don’t usually perform the same way. If one part of a portfolio is declining in value, it can hopefully be offset by another part that’s rising. Although having a diversified portfolio doesn’t guarantee positive investment performance, the principle of diversification is widely used in investing to construct portfolios that have a better chance of weathering changing economic cycles. 


One common approach to building a diversified portfolio is to add bonds—which are typically low-risk assets with moderate returns—to a portfolio of stocks—which are generally higher returning but also higher risk. Diversifying between stocks and bonds may help shield a portfolio from deeper losses if stocks suddenly decline.

A traditional balanced portfolio puts a greater emphasis on stocks to generate growth while maintaining a sizable exposure to bonds to help lower overall risk

A traditional diversified portfolio typically has 60% invested in stocks and 40% in bonds
Source: John Hancock Investment Management, as of 2021.


The merits of this traditional approach to diversifying were most recently demonstrated in early 2020 when the S&P 500 Index declined nearly 30% over a 30-day period, while the Bloomberg U.S. Aggregate Bond Index only lost around 2%.1

In other words, if you invested $100 exclusively in large-cap stocks on March 18, 2020, that $100 would’ve bottomed at close to $70, losing almost 30% in value, while a portfolio that included bonds would’ve lost 18.8%—or 13.7% less—than the stock-only portfolio.The bottom line is that a diversified portfolio may help reduce severe losses—a key objective of many investors looking to protect their overall portfolio. 

Diversifying to build robust investment portfolios

Stocks and bonds are two potential underlying components of a diversified portfolio. But robust diversification may be more effectively achieved when a portfolio takes in a broad spectrum of component investments, not only across but also within asset classes: 


Diversified by:
• Size of company
• Geography
• Sector
• Style


Diversified by:
• Issuer
• Geography
• Duration
• Quality


May include:
• Commodities
• Real estate
• Derivative instruments
• Hedge funds

Diversifying within asset classes may give investors different tools to help enhance portfolio returns or help protect against volatility.

Equity investing across differently sized companies has benefits

Within stocks, investments can be diversified by company size—often referred to as market capitalization, or market cap—from the stable and oftentimes predictable growth of traditional U.S. large-cap companies to mid- and small-cap stocks that may offer more rapid growth potential. A mix of stocks of differently sized companies in markets outside the United States is also increasingly being considered within portfolios for the differentiated returns these components may provide.

Bond investing across issuers, duration, and quality

Investments in bonds—which are part of a large category of fixed-income securities based on different types of debt—may vary by characteristics associated with their duration (interest-rate sensitivity), issuer (corporate, government, or municipal), and quality (the relative likelihood of the issuer defaulting on its debt). This category also includes multitrillion-dollar markets in mortgage-backed securities and derivatives thereof, such as collateralized mortgage obligations.

Alternatives bring something different to the mix

Alternatives­ are an extremely broad asset class that has historically appealed to institutional investors but that now finds expression in products offered to individual investors. Alternatives may help to deliver performance that’s often uncorrelated to traditional stocks and bonds. Uncorrelated assets aren't expected to perform the same way at the same time, thereby acting as good diversifiers when combined in a portfolio. The broader subset of alternatives may include investments in global real estate, infrastructure, hedge funds, private equity, and commodities such as timber and agriculture.

The extent to which each asset class is used in diversifying portfolios is based on investment objective—such as to achieve growth or generate income—as well as risk profile (conservative, moderate, or aggressive).

Diversifying by geography brings another angle to portfolios

Diversifying using non-U.S. assets can help U.S. investors gain access to different sources of investment returns. The case for diversifying by geography is to benefit from the investment opportunities in markets that may have different growth rates, asset classes, dominant sectors, and economic drivers to the home market.

Global markets are commonly divided into three tiers:

  • Developed markets, such as the United States, Canada, Japan, Singapore, Western Europe, the United Kingdom, Australia, and New Zealand
  • Emerging markets, such as Brazil, China, India, South Africa, and Russia
  • Frontier markets, including, but not limited to, several pan-African countries, Thailand, Vietnam, Pakistan, and Panama

Developed markets tend to have lower unemployment, inflation and interest rates than emerging and frontier markets. Historically, they've also had higher GDP, but more recently emerging markets have been contributing an ever greater share of global GDP, making these markets a more permanent feature in investors' considerations.

Top 10 largest economies globally by % of global GDP includes sizable emerging markets

Included in the top 10 largest economies globally by percentage of global GDP are the emerging markets of China, India and Brazil
Source: The World Bank Data, World Bank, OECD, John Hancock Investment Management. All data as of 2020, Japan GDP as of 2019.


Emerging and frontier markets offer investors a different set of investment opportunities. Higher interest rates is one positive for global fixed-income investors, while GDP is not only increasing in global share but also generally grows at a faster rate. In the decade before the start of COVID-19, China and India's GDP grew annually by 5.6% and 3.0%, respectively. In contrast, average annual GDP growth in some of the developed markets was much lower, such as in Germany (0.30%), Japan (0.50%), and the United Kingdom (0.80%).3

Diversifying by sector and industry helps weather economic cycles

The aim of diversifying across sectors is to gain exposure to industries that are performing well at a particular point in an economic cycle while maintaining exposure to others that may perform better in the future.

Industries that perform poorly at one point in a cycle could recover rapidly as economic conditions change; for example, discretionary spending in restaurants may drop when an economy is going through a dip, while supermarket spending remains strong as food and other basics are essential items. In a recovery, discretionary spending often rebounds quickly and strongly, so U.S. equity investors with exposure to the consumer discretionary sector from the outset would be best placed to benefit from its early recovery.

Diversifying by investment style broadens an investment approach

Diversifying by investment style gives investors exposure to assets that are grouped by specific common characteristics. While there’s no set definition, growth stocks are generally considered to be the stocks of companies that are anticipated to grow rapidly and therefore generate revenue and earnings at an above-average rate, while value stocks generally represent well-established firms that often pay high dividend yields and generate steady earnings that are typically slower growing than those of growth stocks.

Investment style also refers to the different approaches portfolio managers may adopt to access specific opportunities. Some managers take an active investing approach, where specific securities are chosen based on in-depth research and analysis; others take a passive investing approach, which typically constitutes investing in stocks that also constitute an index that tracks a set of securities determined by certain rules around market cap, style, and geography.

Both approaches could have merit and specific roles within a portfolio. For some investment opportunities, an active approach may be better, while for others, a lower-cost passive option may be preferable.

Putting it all together: asset allocation

Creating a diversified portfolio isn’t always a simple endeavor. When you consider that it involves spreading your investments across multiple asset classes, how you determine the degree of each exposure is the million-dollar question. That’s where a financial professional can play a key role for investors.

A combination of factors, including an investor’s time horizon and investment objectives—capital accumulation, preservation, or income generation—is the key ingredient in determining optimal asset allocation and diversification that align with an individual’s overall risk profile.

Portfolios diversified across a broad spectrum of investment components according to risk profile4

Portfolio diversified across a broad spectrum of investment components can include equities, fixed income and alternative investments, which can be diversified according to investors' risk profiles
Source: John Hancock Investment Management, 2021. For illustrative purposes only. 

Diversification: a powerful tool in investing

All investments carry some level of risk, whether investing in a stock or a bond or buying a house. While investors can seek to mitigate these risks through diversification, it can never completely free an investor of risk. However, when created judiciously, a diversified portfolio can lower investment risk across market cycles and help raise the chance of accessing opportunities when they arise in different market segments.

1 Bloomberg, as of 3/18/20. 2 Large-cap stocks are represented by the S&P 500 Index, which tracks the performance of 500 of the largest publicly traded companies in the United States. Bonds are represented by the Bloomberg U.S. Aggregate Bond Index, which tracks the performance of U.S. investment-grade bonds in government, asset-backed, and corporate debt markets. It is not possible to invest directly in an index. 3 GDP per capita growth (annual %) 2009–2019, The World Bank Data, World Bank, OECD, John Hancock Investment Management, as of 2021. 4 John Hancock Investment Management, as of 12/31/20. Allocation figures are rounded to the nearest whole number. Allocations less than 5% are not labeled within the charts.

Investing involves risks, including the potential loss of principal. Past performance does not guarantee future results. Large company stocks could fall out of favor. The stock prices of midsize and small companies can change more frequently and dramatically than those of large companies. Fund distributions generally depend on income from underlying investments and may vary or cease altogether in the future. A portfolio concentrated in one sector or that holds a limited number of securities may fluctuate more than a diversified portfolio. Value stocks may decline in price.

Uncorrelated assets are assets that don’t move in the same direction or that are not expected to perform in the same way at the time same time. Standard deviation is a statistical measure of the historic volatility of a portfolio. It measures the fluctuation of a fund’s periodic returns from the mean or average. The larger the deviation, the larger the standard deviation and the higher the risk. Collateralized mortgage obligations (CMOs) are more complicated versions of mortgage-backed securities that consist of multiple classes of securities designed to appeal to investors with different investment objectives and risk tolerances. Portfolios that have a greater percentage of alternatives may have greater risks. Diversification does not guarantee a profit or eliminate the risk of a loss.