ATO vs. ^GSPC

Last updated Jun 3, 2026

ATO (Atmos Energy Corporation) is a stock, while ^GSPC (S&P 500 Index) is an index. Over the past 10 years, ATO returned 11.08%/yr vs 13.75%/yr for ^GSPC. At a 0.33 correlation, their price movements are largely independent.

Performance

ATO vs. ^GSPC - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Atmos Energy Corporation (ATO) and S&P 500 Index (^GSPC). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, ATO achieves a 1.80% return, which is significantly lower than ^GSPC's 11.16% return. Over the past 10 years, ATO has underperformed ^GSPC with an annualized return of 11.08%, while ^GSPC has yielded a comparatively higher 13.75% annualized return.

ATO

• 1D: 0.96%
• 1M: -9.99%
• YTD: 1.80%
• 6M: 0.33%
• 1Y: 11.56%
• 3Y*: 16.60%
• 5Y*: 13.55%
• 10Y*: 11.08%

^GSPC

• 1D: 0.13%
• 1M: 5.25%
• YTD: 11.16%
• 6M: 11.43%
• 1Y: 28.20%
• 3Y*: 21.12%
• 5Y*: 12.66%
• 10Y*: 13.75%

*Multi-year figures are annualized to reflect compound growth (CAGR)

ATO vs. ^GSPC - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
ATO Atmos Energy Corporation	1.80%	23.07%	23.35%	6.17%	9.63%	12.75%	-12.73%	23.14%	10.39%	18.41%
^GSPC S&P 500 Index	11.16%	16.39%	23.31%	24.23%	-19.44%	26.89%	16.26%	28.88%	-6.24%	19.42%

Correlation

The correlation between ATO and ^GSPC is -0.01, meaning there is essentially no relationship between their price movements. Each responds to its own set of market drivers, making them strong candidates for combining in a diversified portfolio.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	-0.01
Correlation (3Y) Calculated over the trailing 3-year period	0.15
Correlation (5Y) Calculated over the trailing 5-year period	0.26
Correlation (10Y) Calculated over the trailing 10-year period	0.27
Correlation (All Time) Calculated using the full available price history since Jan 5, 1987	0.33

The correlation between ATO and ^GSPC shifts across timeframes, from -0.01 (1 year) to 0.33 (all time), reflecting how their relationship changes across market environments.

Return for Risk

ATO vs. ^GSPC — Risk / Return Rank

Compare risk-adjusted metric ranks to identify better-performing investments over the past 12 months.

ATO

ATO Risk / Return Rank: 60
ATO Sharpe Ratio Rank: 64
ATO Sortino Ratio Rank: 56
ATO Omega Ratio Rank: 54
ATO Calmar Ratio Rank: 60
ATO Martin Ratio Rank: 67

^GSPC

^GSPC Risk / Return Rank: 79
^GSPC Sharpe Ratio Rank: 76
^GSPC Sortino Ratio Rank: 76
^GSPC Omega Ratio Rank: 77
^GSPC Calmar Ratio Rank: 79
^GSPC Martin Ratio Rank: 88

The rank (0–100) shows how this investment's returns compare to the risk taken. Higher = better. Based on the past 12 months of data, combining Sharpe, Sortino, and other metrics used by quantitative funds and institutional investors.

ATO vs. ^GSPC - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Atmos Energy Corporation (ATO) and S&P 500 Index (^GSPC). Risk-adjusted metrics are performance indicators that assess an investment's returns in relation to its risk, enabling a more accurate comparison of different investment options.

	ATO	^GSPC	Difference
Sharpe ratio Return per unit of total volatility	0.75	2.39	-1.64
Sortino ratio Return per unit of downside risk	1.12	3.25	-2.13
Omega ratio Gain probability vs. loss probability	1.14	1.43	-0.30
Calmar ratio Return relative to maximum drawdown	0.92	3.16	-2.24
Martin ratio Return relative to average drawdown	3.18	14.61	-11.43
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

ATO vs. ^GSPC - Sharpe Ratio Comparison

The current ATO Sharpe Ratio is 0.75, which is lower than the ^GSPC Sharpe Ratio of 2.39. The chart below compares the historical Sharpe Ratios of ATO and ^GSPC, calculated using daily returns over the previous 12 months. A higher Sharpe Ratio indicates better risk-adjusted performance relative to the risk-free rate.

Sharpe Ratios by Period

	ATO	^GSPC	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	0.75	2.39	-1.64
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.73	0.75	-0.02
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.52	0.76	-0.24
Sharpe Ratio (All Time) Calculated using the full available price history	0.52	0.47	+0.05

Drawdowns

ATO vs. ^GSPC - Drawdown Comparison

The maximum ATO drawdown since its inception was -51.94%, smaller than the maximum ^GSPC drawdown of -56.78%. Use the drawdown chart below to compare losses from any high point for ATO and ^GSPC.

Drawdown Indicators

	ATO	^GSPC	Difference
Max Drawdown Largest peak-to-trough decline	-51.94%	-56.78%	+4.84%
Max Drawdown (1Y) Largest decline over 1 year	-12.58%	-9.10%	-3.48%
Max Drawdown (3Y) Largest decline over 3 years	-16.87%	-18.90%	+2.03%
Max Drawdown (5Y) Largest decline over 5 years	-19.08%	-25.43%	+6.35%
Max Drawdown (10Y) Largest decline over 10 years	-32.91%	-33.92%	+1.01%
Current Drawdown Current decline from peak	-11.75%	0.00%	-11.75%
Average Drawdown Average peak-to-trough decline	-8.56%	-10.72%	+2.16%
Ulcer Index Depth and duration of drawdowns from previous peaks	3.62%	1.97%	+1.65%

Volatility

ATO vs. ^GSPC - Volatility Comparison

Atmos Energy Corporation (ATO) has a higher volatility of 4.87% compared to S&P 500 Index (^GSPC) at 2.84%. This indicates that ATO's price experiences larger fluctuations and is considered to be riskier than ^GSPC based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	ATO	^GSPC	Difference
Volatility (1M) Calculated over the trailing 1-month period	4.87%	2.84%	+2.03%
Volatility (6M) Calculated over the trailing 6-month period	11.64%	8.98%	+2.66%
Volatility (1Y) Calculated over the trailing 1-year period	15.44%	11.87%	+3.57%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	18.57%	16.90%	+1.67%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	21.25%	18.07%	+3.18%

Frequently Asked Questions

Can I hold both ATO and ^GSPC in my portfolio?

ATO and ^GSPC have a correlation of -0.01, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, ATO or ^GSPC?

ATO has higher volatility (4.87%) compared to ^GSPC (2.84%). In terms of maximum drawdown, ATO dropped -51.94% vs ^GSPC's -56.78%.

Which has better risk-adjusted returns?

^GSPC currently has the higher Sharpe Ratio (2.39 vs 0.75), meaning it's delivered slightly more return per unit of risk over the trailing 12 months. However, this ranking shifts over time - use the Risk/Return Score above for a more comprehensive view that combines Sharpe, Sortino, and other measures used by quantitative funds.