Disciplined Growth Investors holds 1.10M shares of Geospace (NASDAQ: GEOS) — 8.5%

Rhea-AI Filing Summary

Disciplined Growth Investors, Inc. reports beneficial ownership of 1,101,426 shares of Geospace Technologies Corp common stock, representing 8.5% of the class as of 03/31/2026. The filing states the fund holds sole voting power and sole dispositive power over all 1,101,426 shares. This amendment to the Schedule 13G/A updates the ownership disclosure and is signed by the filer’s Chief Operating & Compliance Officer on 05/15/2026.

Insights

Institutional Ownership Analyst

Large passive stake disclosed: 1,101,426 shares (8.5%) as of 03/31/2026.

Disciplined Growth Investors, Inc. is recorded as beneficial owner of 1,101,426 shares with sole voting and dispositive power. The filing is an amendment to a Schedule 13G/A, indicating an updated ownership report rather than a transaction description.

Public filings will show whether this holding affects reported institutional ownership percentages; subsequent filings may reveal changes in position or additional disclosures.

Corporate Governance Specialist

Filed amendment clarifies control rights: sole voting and dispositive authority over the disclosed shares.

The disclosure specifies both sole voting power and sole dispositive power for the same 1,101,426 shares, which signals the filer can vote and direct dispositions of these shares. The Schedule 13G/A form type is typically used for passive investors but can be amended when holdings change.

Stake size of 8.5% may require monitoring in future filings for any shift to active status or changes in ownership thresholds.

Key Figures

Filing type: Schedule 13G/A (Amendment No. 10) Shares beneficially owned: 1,101,426 shares Percent of class: 8.5% +2 more

5 metrics

Filing type Schedule 13G/A (Amendment No. 10) ownership disclosure update

Shares beneficially owned 1,101,426 shares as of <date>03/31/2026</date>

Percent of class 8.5% percent of common stock class as reported

Voting power 1,101,426 shares (sole) sole voting power reported

Dispositive power 1,101,426 shares (sole) sole dispositive power reported

Key Terms

Schedule 13G/A, Beneficial ownership, Sole dispositive power, Sole voting power

4 terms

Schedule 13G/A regulatory

"Amendment No. 10 and Schedule 13G/A heading"

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

"Item 4(a) Amount beneficially owned: 1,101,426"

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.

Sole dispositive power regulatory

"Item 4(c)(iii) Sole power to dispose: 1,101,426"

Sole dispositive power is the exclusive legal authority to decide what happens to a security — for example, whether to sell, transfer, or retain shares — without needing anyone else’s permission. Investors care because it signals who truly controls the economic outcome of an investment: like holding the only key to a safe, the holder can realize gains or losses and may trigger regulatory reporting, insider rules, or influence over corporate ownership.

Sole voting power regulatory

"Item 4(c)(i) Sole power to vote: 1,101,426"

Sole voting power is the exclusive right to cast votes attached to a shareholder’s stock without needing approval from anyone else. Like holding the only remote control for a TV, it lets that holder decide corporate matters such as board members, mergers, and policy changes, making it important to investors because it concentrates control and can strongly influence a company’s strategy and the value of its shares.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 10)

GEOSPACE TECHNOLOGIES CORP

(Name of Issuer)

Common Stock

(Title of Class of Securities)

37364X109

(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): 37364X109

1

Names of Reporting Persons

DISCIPLINED GROWTH INVESTORS INC /MN

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

MINNESOTA

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 1,101,426.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 1,101,426.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,101,426.00

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)

8.5 %

12

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13G

Item 1.
(a)	Name of issuer: GEOSPACE TECHNOLOGIES CORP
(b)	Address of issuer's principal executive offices: 7007 PINEMONT DR., 7007 PINEMONT DR., HOUSTON, TEXAS, 77040.
Item 2.
(a)	Name of person filing: Disciplined Growth Investors, Inc.
(b)	Address or principal business office or, if none, residence: 150 South Fifth Street, Suite 2550 Minneapolis, MN 55402
(c)	Citizenship: Minnesota, USA
(d)	Title of class of securities: Common Stock
(e)	CUSIP No.: 37364X109
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: 1,101,426
(b)	Percent of class: 8.5%
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 1,101,426
	(ii) Shared power to vote or to direct the vote: 0
	(iii) Sole power to dispose or to direct the disposition of: 1,101,426
	(iv) Shared power to dispose or to direct the disposition of: 0
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:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.

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.

DISCIPLINED GROWTH INVESTORS INC /MN

Signature:	Peter G. Rieke
Name/Title:	Chief Operating & Compliance Officer
Date:	05/15/2026

FAQ

What stake does Disciplined Growth Investors hold in GEOS?

They beneficially own 1,101,426 shares, equal to 8.5% of Geospace Technologies Corp common stock as of 03/31/2026. The Schedule 13G/A amendment reports sole voting and dispositive power over these shares.

Does the filing show who controls voting of the shares?

Yes. The filing states the filer has sole voting power over all 1,101,426 shares. It also reports sole dispositive power, meaning the filer can direct disposition of those shares.

What form was filed to disclose this ownership?

An amended Schedule 13G/A (Amendment No. 10) was filed to update ownership details. The amendment format is used to report changes in beneficial ownership by certain large holders.

What are the relevant dates in the filing?

The ownership figure is reported as of 03/31/2026 and the filing is signed by the filer’s officer on 05/15/2026. These dates anchor the reported position and the amendment's execution.

Does this filing indicate any share purchases or sales?

No. The Schedule 13G/A amendment discloses beneficial ownership and control powers; it does not describe specific purchase or sale transactions in this excerpt.