ACLS vs. VOO

Last updated Jun 4, 2026

ACLS (Axcelis Technologies, Inc.) is a stock, while VOO (Vanguard S&P 500 ETF) is S&P 500 fund tracking the S&P 500 Index. Over the past 10 years, ACLS returned 30.54%/yr vs 15.56%/yr for VOO. A 0.54 correlation means they provide meaningful diversification when combined.

Performance

ACLS vs. VOO - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Axcelis Technologies, Inc. (ACLS) and Vanguard S&P 500 ETF (VOO). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, ACLS achieves a 98.15% return, which is significantly higher than VOO's 10.91% return. Over the past 10 years, ACLS has outperformed VOO with an annualized return of 30.54%, while VOO has yielded a comparatively lower 15.56% annualized return.

ACLS

• 1D: 0.26%
• 1M: 12.21%
• YTD: 98.15%
• 6M: 80.86%
• 1Y: 168.58%
• 3Y*: -0.66%
• 5Y*: 30.84%
• 10Y*: 30.54%

VOO

• 1D: -0.70%
• 1M: 5.04%
• YTD: 10.91%
• 6M: 10.93%
• 1Y: 28.04%
• 3Y*: 22.44%
• 5Y*: 13.90%
• 10Y*: 15.56%

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

ACLS vs. VOO - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
ACLS Axcelis Technologies, Inc.	98.15%	14.98%	-46.13%	63.42%	6.44%	156.04%	20.83%	35.39%	-37.98%	97.25%
VOO Vanguard S&P 500 ETF	10.91%	17.82%	24.98%	26.32%	-18.17%	28.79%	18.32%	31.37%	-4.50%	21.77%

Correlation

The correlation between ACLS and VOO is 0.51, which is moderate. They share some common price drivers but move independently often enough to provide real diversification benefit when combined.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.51
Correlation (3Y) Calculated over the trailing 3-year period	0.58
Correlation (5Y) Calculated over the trailing 5-year period	0.63
Correlation (10Y) Calculated over the trailing 10-year period	0.59
Correlation (All Time) Calculated using the full available price history since Sep 10, 2010	0.54

The correlation between ACLS and VOO shifts across timeframes, from 0.51 (1 year) to 0.63 (5 years), reflecting how their relationship changes across market environments.

Return for Risk

ACLS vs. VOO — Risk / Return Rank

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

ACLS

ACLS Risk / Return Rank: 92
ACLS Sharpe Ratio Rank: 94
ACLS Sortino Ratio Rank: 91
ACLS Omega Ratio Rank: 89
ACLS Calmar Ratio Rank: 94
ACLS Martin Ratio Rank: 92

VOO

VOO Risk / Return Rank: 70
VOO Sharpe Ratio Rank: 71
VOO Sortino Ratio Rank: 70
VOO Omega Ratio Rank: 70
VOO Calmar Ratio Rank: 62
VOO Martin Ratio Rank: 75

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.

ACLS vs. VOO - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Axcelis Technologies, Inc. (ACLS) and Vanguard S&P 500 ETF (VOO). 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.

	ACLS	VOO	Difference
Sharpe ratio Return per unit of total volatility	2.99	2.39	+0.60
Sortino ratio Return per unit of downside risk	3.39	3.25	+0.14
Omega ratio Gain probability vs. loss probability	1.43	1.43	0.00
Calmar ratio Return relative to maximum drawdown	6.47	3.16	+3.31
Martin ratio Return relative to average drawdown	15.03	14.73	+0.31
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

ACLS vs. VOO - Sharpe Ratio Comparison

The current ACLS Sharpe Ratio is 2.99, which is comparable to the VOO Sharpe Ratio of 2.39. The chart below compares the historical Sharpe Ratios of ACLS and VOO, 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

	ACLS	VOO	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	2.99	2.39	+0.60
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.57	0.83	-0.26
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.57	0.87	-0.29
Sharpe Ratio (All Time) Calculated using the full available price history	0.03	0.89	-0.86

Drawdowns

ACLS vs. VOO - Drawdown Comparison

The maximum ACLS drawdown since its inception was -99.34%, which is greater than VOO's maximum drawdown of -33.99%. Use the drawdown chart below to compare losses from any high point for ACLS and VOO.

Drawdown Indicators

	ACLS	VOO	Difference
Max Drawdown Largest peak-to-trough decline	-99.34%	-33.99%	-65.35%
Max Drawdown (1Y) Largest decline over 1 year	-26.20%	-8.90%	-17.30%
Max Drawdown (3Y) Largest decline over 3 years	-78.84%	-18.69%	-60.15%
Max Drawdown (5Y) Largest decline over 5 years	-78.84%	-24.52%	-54.32%
Max Drawdown (10Y) Largest decline over 10 years	-78.84%	-33.99%	-44.85%
Current Drawdown Current decline from peak	-20.60%	-0.70%	-19.90%
Average Drawdown Average peak-to-trough decline	-72.37%	-3.69%	-68.68%
Ulcer Index Depth and duration of drawdowns from previous peaks	11.26%	1.91%	+9.35%

Volatility

ACLS vs. VOO - Volatility Comparison

Axcelis Technologies, Inc. (ACLS) has a higher volatility of 25.94% compared to Vanguard S&P 500 ETF (VOO) at 2.84%. This indicates that ACLS's price experiences larger fluctuations and is considered to be riskier than VOO based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	ACLS	VOO	Difference
Volatility (1M) Calculated over the trailing 1-month period	25.94%	2.84%	+23.10%
Volatility (6M) Calculated over the trailing 6-month period	45.82%	8.90%	+36.92%
Volatility (1Y) Calculated over the trailing 1-year period	57.01%	11.80%	+45.21%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	54.63%	16.81%	+37.82%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	53.35%	18.01%	+35.34%

Dividends

ACLS vs. VOO - Dividend Comparison

ACLS has not paid dividends to shareholders, while VOO's dividend yield for the trailing twelve months is around 1.03%.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
ACLS Axcelis Technologies, Inc.	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%
VOO Vanguard S&P 500 ETF	1.03%	1.13%	1.24%	1.46%	1.69%	1.25%	1.54%	1.88%	2.06%	1.78%	2.02%	2.10%

Frequently Asked Questions

Can I hold both ACLS and VOO in my portfolio?

ACLS and VOO have a correlation of 0.51, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, ACLS or VOO?

ACLS has higher volatility (25.94%) compared to VOO (2.84%). In terms of maximum drawdown, ACLS dropped -99.34% vs VOO's -33.99%.

Which has better risk-adjusted returns?

ACLS currently has the higher Sharpe Ratio (2.99 vs 2.39), 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.