SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

Amendment #1

Under the Securities and Exchange Act of 1934

PubMatic Inc

(Name of Issuer)

Class A Common Stock

(Title of Class of Securities)

74467Q103

(CUSIP Number)

January 31, 2021

(Date of Event Which Requires Filing of this Statement)

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

This Schedule is filed pursuant to Rule 13d-1(b)

The information required in the remainder of this cover page (except any items to which the form provides a cross-reference) 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.

CUSIP NO. 74467Q103

CUSIP NO. 74467Q103

CUSIP NO. 74467Q103

(a) Ameriprise Financial, Inc.

A parent holding company in accordance with Rule 13d-1(b)(1)(ii)(G). (Note: See Item 7)

(b) Columbia Management Investment Advisers, LLC

An investment adviser in accordance with Rule 13d-1(b)(1)(ii)(E).

(c) Columbia Small Cap Growth Fund I

An investment company in accordance with Rule 13d-1(b)(1)(ii)(D).

CMIA and AFI do not directly own any shares of Common Stock of the issuer. As the investment adviser to the Fund and various other unregistered and registered investment companies and other managed accounts, CMIA may be deemed to beneficially own the shares reported herein by the Fund. Accordingly, the shares reported herein by CMIA include those shares separately reported herein by the Fund.

As the parent holding company of CMIA, AFI may be deemed to beneficially own the shares reported herein by CMIA. Accordingly, the shares reported herein by AFI include those shares separately reported herein by CMIA.

Each of AFI and CMIA, and the subsidiaries identified on the attached Exhibit I, disclaims beneficial ownership of any shares reported on this Schedule.

To the knowledge of AFI, CMIA and the Fund, no other persons besides AFI, CMIA and the Fund and those persons for whose shares of common stock CMIA and AFI report beneficial ownership have the right to receive or the power to direct the receipt of dividends from or the proceeds from the sale of the securities of the issuer reported herein. As of January 31, 2021, only the Fund owned more than 5% of the class of securities reported herein.

Any remaining shares reported herein by CMIA are held by various other funds or accounts managed by CMIA which each have the right to receive any dividends paid by the issuer and could terminate their respective investment advisory relationship with CMIA and then subsequently direct the use of proceeds from the sale of the common stock owned by such fund or account. To CMIA’s knowledge, none of these other funds or accounts own more than 5% of the outstanding shares of the issuer as January 31, 2021.

AFI: See Exhibit I

Not Applicable

Not Applicable

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired in the ordinary course of business and were not acquired for the purpose of and do not have the effect of changing or influencing the control of the issuer of such securities and were not acquired in connection with or as a participant in any transaction having such purposes or effect.

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.

Dated: Feburay 10, 2021

Exhibit Index

Exhibit I

to

Schedule 13G

Ameriprise Financial, Inc., a Delaware Corporation, is a parent holding company. The classification and identity of the relevant subsidiaries is as follows:

Investment Adviser – Columbia Management Investment Advisers, LLC is an investment adviser registered under section 203 of the Investment Advisers Act of 1940.

Exhibit II

to

Schedule 13G

Joint Filing Agreement

The undersigned persons agree and consent to the joint filing on their behalf of this Schedule 13G dated Feburay 10, 2021 in connection with their beneficial ownership of PubMatic Inc. Each of Columbia Small Cap Growth Fund I and Columbia Management Investment Advisers, LLC authorizes Ameriprise Financial, Inc. to execute the Schedule 13G to which this Exhibit is attached and make any necessary amendments thereto.