Summit holds 29.2M LifeStance shares (NASDAQ: LFST) in Schedule 13G/A

Rhea-AI Filing Summary

Summit Partners and affiliated funds reported shared beneficial ownership of LifeStance Health Group common stock. Summit Partners, L.P. has 29,209,776 shares with shared voting and dispositive power, representing 7.49% of the class. The filing cites 389,783,210 shares outstanding as of February 17, 2026.

The Schedule 13G/A lists related Summit entities (including Growth Equity Fund IX‑A and IX‑B) with shared holdings of 17,886,858 and 11,168,308 shares respectively and explains the fund/committee voting structure and delegations.

Key Figures

Shares outstanding: 389,783,210 shares Summit Partners, L.P. shared holdings: 29,209,776 shares Summit Growth Equity Fund IX-A: 17,886,858 shares +1 more

4 metrics

Shares outstanding 389,783,210 shares as of February 17, 2026 (source: cited Form 10-K)

Summit Partners, L.P. shared holdings 29,209,776 shares shared voting and dispositive power reported in Schedule 13G/A

Summit Growth Equity Fund IX-A 17,886,858 shares shared voting and dispositive power reported

Summit Growth Equity Fund IX-B 11,168,308 shares shared voting and dispositive power reported

Key Terms

Schedule 13G/A, beneficial ownership, shared dispositive power, investment committee

4 terms

Schedule 13G/A regulatory

"This statement is filed by the entities and persons listed below"

A Schedule 13G/A is an amended public filing with the U.S. securities regulator that updates a previous Schedule 13G, disclosing when an individual or group holds a substantial (typically over 5%) stake in a company and is claiming a passive, non‑controlling intent. Investors monitor these updates because rising or falling holdings can signal changing confidence, potential future moves, or shifts in voting power — like watching a public ledger where large shareholders quietly adjust their positions.

beneficial ownership financial

"Amount beneficially owned: See responses to Item 9 on each cover page"

Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.

shared dispositive power financial

"Shared Dispositive Power 29,209,776.00"

investment committee other

"delegated investment decisions... through a three-person investment committee"

An investment committee is a small group of experienced people who set the rules and make the key decisions about what investments to buy, hold, or sell for a fund, pension, or portfolio. Think of them as the steering team that balances goals, potential returns and risk—their choices shape how much money investors are likely to gain or lose and provide consistent oversight so decisions aren’t made impulsively.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 05/08/2026 - 04:48 PM Learn about SEC filing dates

FAQ

What stake does Summit Partners report in LifeStance (LFST)?

Summit Partners, L.P. reports shared beneficial ownership of 29,209,776 shares, about 7.49% of the class. The figure is calculated from 389,783,210 shares outstanding as of February 17, 2026, per the filing's cited Form 10‑K.

Which Summit funds are listed and how many shares do they hold?

The filing names Summit Partners Growth Equity Fund IX‑A (17,886,858 shares) and IX‑B (11,168,308 shares). It also lists smaller related entities with voting/dispositive power allocations and shared ownership arrangements.

Does Summit claim sole control over these LifeStance shares?

No. The filing states shared voting and dispositive power for the reported shares and describes delegation to an investment committee of Summit Partners, with members who may be deemed to have authority.

What outstanding share count is the percentage based on?

The ownership percentages are calculated using 389,783,210 shares outstanding as of February 17, 2026, as reported in the company’s Form 10‑K filed February 25, 2026, which the Schedule 13G/A cites.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 3)

LifeStance Health Group, Inc.

(Name of Issuer)

Common Stock, par value $0.01 per share

(Title of Class of Securities)

53228F101

(CUSIP Number)

03/31/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): 53228F101

1

Names of Reporting Persons

Summit Partners, L.P.

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 29,209,776.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 29,209,776.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

29,209,776.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

7.49 %

12

Type of Reporting Person (See Instructions)

PN

Comment for Type of Reporting Person: *Calculated based on 389,783,210 shares of common stock, par value $0.01 per share ("Common Stock") outstanding as of February 17, 2026, as reported on the Issuer's Form 10-K, filed with the Securities and Exchange Commission ("SEC") on February 25, 2026.

SCHEDULE 13G

CUSIP Number(s): 53228F101

1

Names of Reporting Persons

Summit Partners Growth Equity Fund IX-A, L.P.

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 17,886,858.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 17,886,858.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

17,886,858.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

4.59 %

12

Type of Reporting Person (See Instructions)

PN

Comment for Type of Reporting Person: *Calculated based on 389,783,210 shares of Common Stock outstanding as of February 17, 2026, as reported on the Issuer's Form 10-K, filed with the SEC on February 25, 2026.

SCHEDULE 13G

CUSIP Number(s): 53228F101

1

Names of Reporting Persons

Summit Partners Growth Equity Fund IX-B, L.P.

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 11,168,308.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 11,168,308.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

11,168,308.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

2.87 %

12

Type of Reporting Person (See Instructions)

PN

Comment for Type of Reporting Person: *Calculated based on 389,783,210 shares of Common Stock outstanding as of February 17, 2026, as reported on the Issuer's Form 10-K, filed with the SEC on February 25, 2026.

SCHEDULE 13G

CUSIP Number(s): 53228F101

1

Names of Reporting Persons

Summit Investors GE IX/VC IV (UK), L.P.

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

CAYMAN ISLANDS

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 13,062.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 13,062.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

13,062.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

0.00 %

12

Type of Reporting Person (See Instructions)

PN

Comment for Type of Reporting Person: *Calculated based on 389,783,210 shares of Common Stock outstanding as of February 17, 2026, as reported on the Issuer's Form 10-K, filed with the SEC on February 25, 2026.

SCHEDULE 13G

CUSIP Number(s): 53228F101

1

Names of Reporting Persons

Summit Partners Entrepreneur Advisors Fund II, L.P.

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 16,691.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 16,691.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

16,691.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

0.00 %

12

Type of Reporting Person (See Instructions)

PN

Comment for Type of Reporting Person: *Calculated based on 389,783,210 shares of Common Stock outstanding as of February 17, 2026, as reported on the Issuer's Form 10-K, filed with the SEC on February 25, 2026.

SCHEDULE 13G

CUSIP Number(s): 53228F101

1

Names of Reporting Persons

Summit Investors GE IX/VC IV, LLC

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 124,857.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 124,857.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

124,857.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

0.03 %

12

Type of Reporting Person (See Instructions)

OO

Comment for Type of Reporting Person: *Calculated based on 389,783,210 shares of Common Stock outstanding as of February 17, 2026, as reported on the Issuer's Form 10-K, filed with the SEC on February 25, 2026.

SCHEDULE 13G

Item 1.
(a)	Name of issuer: LifeStance Health Group, Inc.
(b)	Address of issuer's principal executive offices: 4800 N. Scottsdale Road, Suite 6000 Scottsdale, Arizona 85251
Item 2.
(a)	Name of person filing: This statement is filed by the entities and persons listed below, all of whom together are referred to herein as the "Reporting Persons": (i) Summit Partners, L.P.; (ii) Summit Partners Growth Equity Fund IX-A, L.P.; (iii) Summit Partners Growth Equity Fund IX-B, L.P.; (iv) Summit Investors GE IX/VC IV (UK), L.P.; (v) Summit Partners Entrepreneur Advisors Fund II, L.P.; and (vi) Summit Investors GE IX/VC IV, LLC
(b)	Address or principal business office or, if none, residence: 222 Berkeley Street, 18th Floor Boston, MA 02116
(c)	Citizenship: See response to Item 4 on each cover page
(d)	Title of class of securities: Common Stock, par value $0.01 per share
(e)	CUSIP No.: 53228F101
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: See responses to Item 9 on each cover page.
(b)	Percent of class: See responses to Item 11 on each cover page.
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: See responses to Item 5 on each cover page.
	(ii) Shared power to vote or to direct the vote: See responses to Item 6 on each cover page.
	(iii) Sole power to dispose or to direct the disposition of: See responses to Item 7 on each cover page.
	(iv) Shared power to dispose or to direct the disposition of: See response to Item 8 on each cover page. Summit Partners, L.P. is the managing member of Summit Partners GE IX, LLC, which is general partner of Summit Partners GE IX, L.P., which is the general partner of Summit Partners Growth Equity Fund IX-A, L.P. and Summit Partners Growth Equity Fund IX-B, L.P. Summit Master Company, LLC is (i) the sole member of Summit Partners Entrepreneur Advisors GP II, LLC, which is the general partner of Summit Partners Entrepreneur Advisors Fund II, L.P. and (ii) the general partner of Summit Partners L.P., which is the manager of Summit Investors Management, LLC, which is the manager of Summit Investors GE IX/VC IV, LLC, and the general partner of Summit Investors GE IX/VC IV (UK), L.P. Summit Master Company, LLC, as the sole member of Summit Partners Entrepreneur Advisors GP II, LLC, the managing member of Summit Investors Management, LLC and general partner of Summit Partners, L.P., has delegated investment decisions, including voting and dispositive power, to Summit Partners, L.P. and its investment committee responsible for voting and investment decisions with respect to the reported securities held by Summit Partners, L.P., through a three-person investment committee. Peter Y. Chung, Darren M. Black and Craig D. Frances are the current members of the investment committee, and as such may be deemed to have voting and dispositive authority over the reported securities, but each of the foregoing disclaim such beneficial ownership. This Statement shall not be construed as an admission that the Reporting Persons or any of the members of the investment committee are, for the purpose of Section 13(d) or 13(g) of the Securities Exchange Act of 1934, the beneficial owner of any securities covered by this Statement.
Item 5.	Ownership of 5 Percent or Less of a Class.
	Not Applicable
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	Not Applicable
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.	Certifications:
	Not Applicable

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Summit Partners, L.P.

Signature:	By: Summit Master Company, LLC / /s/ Adam H. Hennessey, as POA
Name/Title:	Its: General Partner / Adam H. Hennessey, as Power of Attorney
Date:	05/08/2026

Summit Partners Growth Equity Fund IX-A, L.P.

Signature:	By: Summit Partners GE IX, L.P. / /s/ Adam H. Hennessey, as POA
Name/Title:	Its: General Partner / Adam H. Hennessey, as Power of Attorney
Date:	05/08/2026

Summit Partners Growth Equity Fund IX-B, L.P.

Signature:	By: Summit Partners GE IX, L.P. / /s/ Adam H. Hennessey, as POA
Name/Title:	Its: General Partner / Adam H. Hennessey, as Power of Attorney
Date:	05/08/2026

Summit Investors GE IX/VC IV (UK), L.P.

Signature:	By: Summit Investors Management, LLC / /s/ Adam H. Hennessey, as POA
Name/Title:	Its: Manager / Adam H. Hennessey, as Power of Attorney
Date:	05/08/2026

Summit Partners Entrepreneur Advisors Fund II, L.P.

Signature:	By: Summit Partners Entrepreneur Advisors GP II, LLC / /s/ Adam H. Hennessey, as POA
Name/Title:	Its: General Partner / Adam H. Hennessey, as Power of Attorney
Date:	05/08/2026

Summit Investors GE IX/VC IV, LLC

Signature:	By: Summit Investors Management, LLC / /s/ Adam H. Hennessey, as POA
Name/Title:	Its: Manager / Adam H. Hennessey, Power of Attorney
Date:	05/08/2026

Exhibit Information

Exhibit A: Joint Filing Agreement, dated as of February 4, 2022, incorporated herein by reference to the statement on Schedule 13G filed by the Reporting Persons on February 4, 2022. Exhibit B: Powers of Attorney, dated as of October 25, 2021, incorporated herein by reference to the statement on Schedule 13G filed by the Reporting Persons on February 4, 2022.