[SCHEDULE 13D/A] Senti Biosciences, Inc. Amended Major Shareholder Report

Rhea-AI Filing Summary

Bayer HealthCare LLC and affiliated reporting persons filed an amended Schedule 13D showing a significant ownership position in Senti Biosciences, Inc. They report beneficial ownership of 6,142,848 shares of common stock, representing 17.82% of the company.

This total includes 3,333,000 shares underlying a warrant for Senti common stock that is exercisable in full within 60 days of the filing date. The ownership percentage is based on 31,144,497 Senti common shares outstanding as of March 19, 2026, as reported in the company’s Form 10-K.

Insights

Equity ownership analyst

Bayer affiliates disclose a 17.82% stake in Senti Biosciences, including warrant-linked shares.

Bayer HealthCare LLC, Bayer US Holding LLC, and two managers report beneficial ownership of 6,142,848 Senti Biosciences shares, equal to 17.82% of the common stock. This figure includes shares already held plus those issuable from a warrant that is exercisable within 60 days.

The filing clarifies that each reporting person disclaims beneficial ownership beyond shares held of record, and that voting and dispositive power over all 6.14M shares is shared, not sole. The stake is calculated against 31,144,497 shares outstanding as of March 19, 2026, giving investors clearer visibility into a large strategic holder’s position.

Key Figures

Beneficial ownership: 6,142,848 shares Ownership percentage: 17.82% Warrant underlying shares: 3,333,000 shares +4 more

7 metrics

Beneficial ownership 6,142,848 shares Total Senti common shares beneficially owned by each reporting person

Ownership percentage 17.82% Percent of Senti common stock reported beneficially owned

Warrant underlying shares 3,333,000 shares Senti common shares underlying Bayer HealthCare LLC warrant, exercisable within 60 days

Shares outstanding 31,144,497 shares Senti common shares outstanding as of March 19, 2026, per Form 10-K

Sole voting power 0 shares Sole power to vote Senti common stock reported by each person

Shared voting power 6,142,848 shares Shares over which reporting persons have shared voting power

Shared dispositive power 6,142,848 shares Shares over which reporting persons share dispositive power

Key Terms

Schedule 13D/A, beneficial ownership, shared voting power, shared dispositive power, +2 more

6 terms

Schedule 13D/A regulatory

"If the filing person has previously filed a statement on Schedule 13G to report the acquisition"

A Schedule 13D/A is an amended disclosure filed with regulators by an investor who already reported owning more than 5% of a company’s shares and needs to update their original filing. Think of it as a public status update that tells markets whether the investor’s ownership, plans, or source of funds have changed; such updates matter because they can signal a push for control, major strategic moves, or increased pressure on management, which can affect stock prices.

beneficial ownership financial

"Each Reporting Person disclaims beneficial ownership of the shares other than those shares which such person owns of record."

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 voting power financial

"Shared Voting Power 6,142,848.00"

Shared voting power occurs when two or more parties jointly have the right to vote or decide how a block of company shares is cast, like co-owners who must agree before moving a piece of furniture. Investors care because who controls voting rights affects board elections, major corporate decisions and takeover outcomes, and shared control can alter regulatory disclosures and the practical influence any holder has over a company’s direction and value.

shared dispositive power financial

"Shared Dispositive Power 6,142,848.00"

warrant financial

"number of shares ... issuable upon the exercise in full of the warrant for Issuer Common Stock held by Bayer Healthcare LLC (the "Warrant")."

A warrant is a time-limited financial contract that gives its holder the right to buy a company's shares at a set price before a specified date, like a coupon that lets you purchase stock at a fixed discount for a limited time. It matters to investors because warrants offer leveraged exposure to a stock’s upside and can dilute existing shareholders if exercised, so they affect potential gains and the company’s outstanding share count.

Registration Rights Agreement regulatory

"Exhibit 7.06 - Registration Rights Agreement (incorporated by reference"

A registration rights agreement is a contract that gives investors the option to have their ownership stakes officially registered with the government, making it easier to sell their shares later. This agreement matters because it provides investors with a clearer path to cash out their investments if they choose, offering more liquidity and confidence in their ability to sell their holdings when desired.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 1)

Senti Biosciences, Inc.

(Name of Issuer)

Common Stock, par value $0.0001 per share

(Title of Class of Securities)

81726A100

(CUSIP Number)

Bayer HealthCare LLC
100 Bayer Boulevard,
Whippany, NJ, 07981
862-404-3000

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

03/27/2026

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

schemaVersion:

SCHEDULE 13D

CUSIP Number(s): 81726A100

1

Name of reporting person

Bayer HealthCare LLC

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 6,142,848.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 6,142,848.00

11

Aggregate amount beneficially owned by each reporting person

6,142,848.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

17.82 %

14

Type of Reporting Person (See Instructions)

CO

Comment for Type of Reporting Person:

The amounts reported in rows 8, 10 and 11 herein include the number of shares of Issuer Common Stock that would be issuable upon the exercise in full of the warrant for Issuer Common Stock held by Bayer Healthcare LLC (the "Warrant"). The amount reported in row 13 herein includes 3,333,000 shares of Issuer Common Stock underlying the Warrant that is exercisable in full within 60 days of the date of this filing.

SCHEDULE 13D

CUSIP Number(s): 81726A100

1

Name of reporting person

Bayer US Holding LLC

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 6,142,848.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 6,142,848.00

11

Aggregate amount beneficially owned by each reporting person

6,142,848.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

17.82 %

14

Type of Reporting Person (See Instructions)

CO

Comment for Type of Reporting Person:

The amounts reported in rows 8, 10 and 11 herein include the number of shares of Issuer Common Stock that would be issuable upon the exercise in full of the Warrant. The amount reported in row 13 herein includes 3,333,000 shares of Issuer Common Stock underlying the Warrant that is exercisable in full within 60 days of the date of this filing.

SCHEDULE 13D

CUSIP Number(s): 81726A100

1

Name of reporting person

Sebastian Guth

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

Unknown

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 6,142,848.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 6,142,848.00

11

Aggregate amount beneficially owned by each reporting person

6,142,848.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

17.82 %

14

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person:

The amounts reported in rows 8, 10 and 11 herein include the number of shares of Issuer Common Stock that would be issuable upon the exercise in full of the Warrant. The amount reported in row 13 herein includes 3,333,000 shares of Issuer Common Stock underlying the Warrant that is exercisable in full within 60 days of the date of this filing.

SCHEDULE 13D

CUSIP Number(s): 81726A100

1

Name of reporting person

Priyal Patel

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

Unknown

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 6,142,848.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 6,142,848.00

11

Aggregate amount beneficially owned by each reporting person

6,142,848.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

17.82 %

14

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person:

The amounts reported in rows 8, 10 and 11 herein include the number of shares of Issuer Common Stock that would be issuable upon the exercise in full of the Warrant. The amount reported in row 13 herein includes 3,333,000 shares of Issuer Common Stock underlying the Warrant that is exercisable in full within 60 days of the date of this filing.

SCHEDULE 13D

Item 1.	Security and Issuer
(a)	Title of Class of Securities: Common Stock, par value $0.0001 per share
(b)	Name of Issuer: Senti Biosciences, Inc.
(c)	Address of Issuer's Principal Executive Offices: 2 Corporate Drive, First Floor, South San Francisco, CALIFORNIA , 94080.
Item 2.	Identity and Background
(a)	Bayer HealthCare LLC ("BHC"); Bayer US Holding LLC ("BUSH LLC"); Sebsatian Guth ("Guth") and Priyal Patel ("Patel", together with Guth, the "Managers of BUSH LLC" and collectively, the Managers of BUSH LLC, along with BHC and BUSH LLC, the "Reporting Persons").
(f)	BHC - Delaware BUSH LLC - Delaware Guth - Unknown Patel - Unknown
Item 5.	Interest in Securities of the Issuer
(a)	BHC - 17.82% BUSH LLC - 17.82% Guth - 17.82% Patel - 17.82% Each Reporting Person disclaims beneficial ownership of the shares other than those shares which such person owns of record. The percentage of outstanding Issuer Common Stock which may be deemed to be beneficially owned by each Reporting Person is set forth on Line 13 of such Reporting Person's cover sheet. Such percentage was calculated based on 31,144,497 shares of Issuer Common Stock reported to be outstanding as of March 19, 2026 on the Issuer's Annual Report on Form 10-K for the period ended December 31, 2025, as filed with the SEC on March 27, 2026.
(b)	Regarding the number of shares as to which such person has: (i) sole power to vote or to direct the vote: See line 7 of cover sheets. (ii) shared power to vote or to direct the vote: See line 8 of cover sheets. (iii) sole power to dispose or to direct the disposition: See line 9 of cover sheets. (iv) shared power to dispose or to direct the disposition: See line 10 of cover sheets.
Item 7.	Material to be Filed as Exhibits.
	Exhibit 7.01 - Joint Filing Agreement by and among the Reporting Persons (incorporated by reference to Exhibit 7.01 of the Schedule 13D filed with the SEC on March 17, 2025). Exhibit 7.02 - Power of Attorney regarding filings under the Securities Exchange Act of 1934, as amended (incorporated by reference to Exhibit 7.02 of the Schedule 13D filed with the SEC on March 17, 2025). Exhibit 7.02(a) - Power of Attorney regarding filings under the Securities Exchange Act of 1334, as amended. Exhibit 7.03 - Certificate of Designation of Preferences, Rights and Limitations of the Series A Convertible Preferred Stock (incorporated by reference to Exhibit 3.1 to the Issuer's Current Report on Form 8-K (File No.001-40440), filed on December 2, 2024). Exhibit 7.04 - Form of Warrant to Purchase Common Stock (incorporated by reference to Exhibit 4.1 to the Issuer's Current Report on Form 8-K (File No.001-40440), filed on December 2, 2024). Exhibit 7.05 - Form of Securities Purchase Agreement, dated December 2, 2024, by and among Senti Biosciences, Inc. and the purchasers named therein (incorporated by reference to Exhibit 10.1 to the Issuer's Current Report on Form 8-K (File No.001-40440), filed on December 2, 2024). Exhibit 7.06 - Registration Rights Agreement (incorporated by reference to Exhibit 10.2 to the Issuer's Current Report on Form 8-K (File No.001-40440), filed on December 2, 2024).

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.

Bayer HealthCare LLC

Signature:	/s/ Priyal Patel
Name/Title:	Priyal Patel, President
Date:	04/16/2026

Bayer US Holding LLC

Signature:	/s/ Sebastian Guth
Name/Title:	Sebastian Guth, President
Date:	04/16/2026

Sebastian Guth

Signature:	/s/ Sebastian Guth
Name/Title:	Sebastian Guth
Date:	04/16/2026

Priyal Patel

Signature:	/s/ Priyal Patel
Name/Title:	Priyal Patel
Date:	04/16/2026