SPY vs SPYM: The Hidden Differences You Need to Know

Ticker Note: State Street has changed the ticker symbol for its lower-cost S&P 500 fund from SPLG to SPYM, effective prior to the open of business on Friday, October 31, 2025.

Two ETFs that look the same but aren’t

Most investors know the SPDR S&P 500 ETF Trust (SPY). It was launched in 1993 by State Street Global Advisors and became the first exchange-traded fund (ETF) ever created.¹ SPY tracks the S&P 500 index, a benchmark that represents roughly 80 percent of the total U.S. equity market. Buying a single share gives an investor ownership in the same 500 companies that shape the American economy.

Over the years, SPY has become a symbol of market efficiency. It manages nearly 700 billion dollars in assets, trades millions of shares every day on major stock exchanges, and sets the standard for ETF liquidity. It is one of the most closely watched funds in the world.

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But there is another option from the same company: the SPDR Portfolio S&P 500 ETF (SPYM). This newer fund, created by State Street Investment Management, holds the exact same stocks as SPY and follows the same S&P 500 index. The key difference is cost. SPYM charges a 0.02 percent expense ratio, while SPY charges 0.0945 percent. That difference sounds small, yet it can translate into thousands of dollars in savings for long-term investors.

Consider an example. An investor who contributes 500 dollars a month for 30 years and earns 10 percent annually would pay around 21 thousand dollars in fees with SPY but only about 5 thousand with SPYM. That sixteen-thousand-dollar gap stays invested, continuing to compound and boost future performance.

This article compares SPY vs SPYM to help you decide which ETF fits your goals. We will look at how their expense ratios, fund structures, and liquidity differ and how those differences can affect long-term results. By understanding what each fund does well, you can choose the version of the S&P 500 ETF that works best for your portfolio and your investing style.

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What SPY and SPYM have in common

At first glance, the SPDR S&P 500 ETF Trust (SPY) and the SPDR Portfolio S&P 500 ETF (SPYM) look identical. Both are managed by State Street Global Advisors, both track the S&P 500 index, and both strive to match the daily performance of America’s largest public companies. Despite being different funds, their structure, holdings, and purpose are closely aligned.

Both track the same S&P 500 index

Each ETF mirrors the S&P 500 index, which represents 500 large-cap U.S. companies that make up roughly 80 percent of the total equity market.² These companies include well-known names such as Apple, Microsoft, Nvidia, Amazon, and Meta Platforms. Because the index is weighted by market capitalization, the largest corporations have the biggest influence on returns.

This approach allows SPY and SPYM to act as complete snapshots of the American economy. Instead of choosing individual stocks, investors can hold one fund that captures broad market exposure across every major sector.

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Same sector allocation and diversification

Table compares the top sector exposures of the SPY and SPYM ETFs based on data as of November 6, 2025.

Sector exposure is nearly identical, led by Information Technology at roughly 36%, followed by Financials, Health Care, Consumer Discretionary, and Communication Services. These figures are as of November 2025, according to State Street’s latest data. The top holdings include Nvidia, Apple, Microsoft, Amazon, and Meta Platforms, each weighted almost identically in both ETFs.

Both funds use full replication, meaning they hold every stock in the S&P 500 index instead of sampling. This approach minimizes tracking error and keeps results aligned with the market. Both pay quarterly dividends, and as of October 30, 2025, the 30-day SEC yield was around 1.0%, though yields vary over time.

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Identical holdings and portfolio structure

The holdings inside both ETFs are the same. They include all 500 companies listed in the S&P 500 index, owned in the same proportions. The top positions typically look like this:

Table compares the top 10 company holdings in the SPY and SPYM ETFs using data as of November 6, 2025.

Because both funds use full replication, they actually hold every security in the index rather than using a sampling approach. That method keeps tracking error extremely low. Investors get precise performance that stays aligned with the overall market.

Same management philosophy

State Street Global Advisors manages both ETFs using the same passive investing discipline. Their approach is straightforward: track the index as closely as possible, minimize costs, and stay fully invested. This strategy has made State Street one of the world’s most trusted names in ETF management.

Whether an investor chooses SPY or SPYM, they are following a proven model designed to capture long-term market performance with minimal friction.

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Consistent dividends and payout schedules

Both SPY and SPYM pay quarterly dividends, which are derived from the income of their underlying holdings. Because they hold the same stocks, the dividend yield is nearly identical, typically between 1.1 and 1.2 percent. Investors can either reinvest those dividends to compound growth or take them as income.

This predictability is part of what makes the S&P 500 ETF such a popular core holding in retirement portfolios. Investors know what they are getting: steady exposure to the market and a consistent stream of dividend income.

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The takeaway

From their holdings to their dividends, these two funds are mirror images of each other. Both deliver the same exposure to the S&P 500 index, the same diversification, and the same long-term performance potential.

The next section looks at where they part ways: cost, structure, and how those differences affect your actual returns.

Key differences that impact performance

Although SPY and SPYM both track the S&P 500 index, a closer look reveals differences that can have a real impact on long-term performance. These details include cost, structure, trading behavior, and how each fund handles dividends and liquidity.

Expense ratio and fund efficiency

The most obvious distinction between the two ETFs is cost. The SPDR S&P 500 ETF Trust (SPY) carries an expense ratio of 0.0945 percent, while the SPDR Portfolio S&P 500 ETF (SPYM) charges just 0.02 percent.

At first, that gap may seem small, but even fractions of a percent add up over time. For every ten thousand dollars invested, SPY costs about nine dollars and forty-five cents per year, while SPYM costs only two dollars. Over thirty years, assuming a ten percent annual return and monthly contributions of five hundred dollars, an investor would save roughly sixteen thousand dollars in fees by choosing SPYM.

Those savings stay invested, earning returns year after year. It is a perfect example of how controlling costs improves fund performance.

Liquidity and trading volume

SPY remains the most traded ETF in the world, with extremely tight bid-ask spreads averaging about 0.005% over 30 days and total trading volume often exceeding $50 billion daily. 

SPYM’s spreads average around 0.016%, which is still considered highly liquid for individual investors. The difference mainly matters to institutions and active traders executing large orders. For most long-term investors, SPYM’s liquidity is more than sufficient.

If you trade frequently or rely on options, SPY SPDR has the advantage. If you are building a long-term portfolio, SPYM is more efficient because of its lower expense ratio.

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Structure and management style

Another key difference lies in each fund’s structure. SPY is organized as a Unit Investment Trust (UIT), a structure created in the early 1990s when ETFs were new. Because of that legacy design, SPY cannot reinvest dividends or engage in securities lending.

SPYM is structured as an open-end ETF, which gives State Street Investment Management more flexibility. It can reinvest dividends, lend securities to generate small amounts of additional income, and manage cash flows more efficiently.³

This open-end design helps SPYM maintain its lower fees and minimize tracking error. The difference may seem minor, but over time it adds up.

Share price and accessibility

The current share price of SPY is around six hundred seventy dollars, while SPYM trades closer to eighty dollars per share. Both represent the same S&P 500 ETF, but the lower entry price of SPYM makes it more accessible for smaller investors or those who invest regularly through dollar-cost averaging.

Lower share prices make it easier to diversify and to allocate across multiple funds without leaving idle cash in a portfolio. Investors using platforms that do not support fractional shares often find SPYM’s pricing more convenient.

Assets under management and scale

SPY has enormous scale, managing nearly seven hundred billion dollars in assets. It is one of the largest funds in the world and sets the benchmark for liquidity. SPYM manages roughly ninety-five billion dollars, which is smaller but still substantial.⁴

The size difference gives SPY a liquidity edge but allows SPYM to operate with leaner costs. Both are fully supported by State Street Global Advisors, and both benefit from institutional-grade oversight and reporting.

Performance and dividends over time

Because both ETFs hold the same stocks, their performance is nearly identical. The only consistent difference is the expense ratio. Over the last decade, SPY produced an annualized return of about 15.15 percent, while SPYM returned 15.23 percent.⁵ That slight edge comes entirely from lower costs and better reinvestment efficiency.

Both funds pay quarterly dividends, but SPYM’s open-end structure allows it to automatically reinvest those dividends, keeping all capital working continuously in the market. SPY’s UIT structure forces dividends to accumulate as cash until distribution, creating a small delay that slightly affects total return.

The difference is subtle but measurable. Over decades, SPYM’s reinvestment advantage compounds into stronger long-term fund performance.

Total cost of ownership

The true cost of an ETF includes both its expense ratio and trading costs. According to State Street Global Advisors, investors who trade frequently may benefit from SPY’s deeper liquidity, while long-term investors save more with SPYM’s minimal fees.

For most people, the deciding factor comes down to how they use the fund. If you want a cost-efficient, set-it-and-forget-it portfolio, SPYM is the better choice. If you need immediate liquidity, institutional-level trading volume, or heavy options activity, SPY remains unmatched.

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Which ETF fits your investing style

Both SPY and SPYM achieve the same goal: broad exposure to the S&P 500 index through a low-cost, diversified ETF. They are managed by the same company, State Street Global Advisors, and they hold the same stocks, but they serve different types of investors.

SPYM: Better for long term investors

If you are a long-term investor who focuses on minimizing costs, SPYM is the better choice. Its 0.02 percent expense ratio is among the lowest of any S&P 500 ETF, which helps your portfolio compound faster over time. The fund’s open-end structure also allows automatic dividend reinvestment, meaning every payout continues to work for you inside the market. That efficiency makes SPYM ideal for retirement accounts, recurring contributions, and anyone who wants simple, low-cost exposure to the U.S. equity market.

SPY: Better for active traders

Tactical investors with shorter holding periods may benefit from SPDR S&P 500 ETF (SPY) due to lower transaction costs despite a higher expense ratio. This example compares trading 50% of a position over one year, showing SPY’s cost efficiency driven by deep market liquidity and narrow bid-ask spreads. Use this data to understand when lower transaction costs outweigh lower management fees.

If you are an active trader or someone who regularly uses options, SPY remains the stronger fit. Its trading volume, liquidity, and deep options market make it perfect for tactical moves, short-term strategies, and large trades that require instant execution. While you pay a slightly higher expense ratio, the ease of trading can offset the difference for those who move in and out of positions frequently.

For investors who like to blend approaches, there is nothing wrong with owning both. You can keep SPYM as your long-term core holding and use SPY for shorter-term trades or hedging. Both funds are backed by the same State Street Investment Management infrastructure and share the same long-term track record of reliable performance.

Whichever you choose, the most important factor is staying invested. Over time, consistency, dividend reinvestment, and disciplined contributions matter more than timing. SPY and SPYM are two of the best tools for capturing the long-term performance of the American market, and both can play a valuable role in a well-constructed portfolio.

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Summary table: SPY vs SPYM

Overview of key fund data points for the SPY and SPYM ETFs, as of November 6, 2025.