UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 12b-25

NOTIFICATION OF LATE FILING

If the notification relates to a portion of the filing checked above, identify the Item(s) to which the notification relates:

PART I — REGISTRANT INFORMATION

ATI Physical Therapy, Inc.

Full Name of Registrant

Fortress Value Acquisition Corp. II

Former Name if Applicable

790 Remington Boulevard

Address of Principal Executive Office (Street and Number)

Bolingbrook, Illinois 60440

City, State and Zip Code

PART II — RULES 12b-25(b) AND (c)

If the subject report could not be filed without unreasonable effort or expense and the registrant seeks relief pursuant to Rule 12b-25(b), the following should be completed. (Check box if appropriate)

PART III — NARRATIVE

State below in reasonable detail why Forms 10-K, 20-F, 11-K, 10-Q, 10-D, N-CEN, N-CSR, or the transition report or portion thereof, could not be filed within the prescribed time period.

(Attach extra Sheets if Needed)

The Registrant is unable to file, without unreasonable effort or expense, its Quarterly Report on Form 10-Q for the quarter ended September 30, 2021) by the prescribed filing date for the reasons stated below.

During the quarter-end closing process, we identified an immaterial prior period error with respect to the amount of the non-cash goodwill impairment charge recorded for the three and six months ended June 30, 2021, specifically related to the assumed benefit to enterprise value as of June 30, 2021 associated with the Company’s net operating loss carryforwards. We evaluated the effects of this error on our previously-issued condensed consolidated financial statements in accordance with the applicable accounting guidance, and concluded that no prior period is materially misstated. The Registrant required more time to finalize its disclosures and the evaluation of the control deficiency related to the revision. The Registrant will file its Form 10-Q within the five calendar day extension period in accordance with Rule 12b-25 of the Securities Exchange Act of 1934.

PART IV — OTHER INFORMATION

Non-GAAP Financial Measures

The following table reconciles the supplemental non-GAAP financial measures, as defined under the rules of the SEC, presented herein to the most directly comparable financial measures calculated and presented in accordance with GAAP. The Company has provided the non-GAAP financial measures, which are not calculated or presented in accordance with GAAP, as supplemental information and in addition to the financial measures that are calculated and presented in accordance with GAAP. EBITDA and Adjusted EBITDA are defined as net income from continuing operations calculated in accordance with GAAP, less net income attributable to non-controlling interests, plus the sum of income tax expense, interest expense, net, depreciation and amortization (“EBITDA”) and further adjusted to exclude certain items of a significant or unusual nature, including but not limited to, goodwill and intangible asset impairment charges, changes in fair value of warrant liability and contingent common shares liability, loss on debt extinguishment, loss on settlement of redeemable preferred stock, business optimization costs, reorganization and severance costs, transaction and integration costs, charges related to lease terminations, share-based compensation, pre-opening de novo costs and non-ordinary legal and regulatory matters (“Adjusted EBITDA”).

We present EBITDA and Adjusted EBITDA because they are key measures used by our management team to evaluate our operating performance, generate future operating plans and make strategic decisions. The Company believes EBITDA and Adjusted EBITDA are useful to investors for the purposes of comparing our results period-to-period and alongside peers and understanding and evaluating our operating results in the same manner as our management team and board of directors.

These supplemental measures should not be considered superior to, as a substitute for or as an alternative to, and should be considered in conjunction with, the GAAP financial measures presented. In addition, since these non-GAAP measures are not determined in accordance with GAAP, they are susceptible to varying calculations and may not be comparable to other similarly titled non-GAAP measures of other companies.

EBITDA and Adjusted EBITDA (Non-GAAP Financial Measures)

The following is a reconciliation of net income (loss), the most directly comparable GAAP financial measure, to EBITDA and Adjusted EBITDA (each of which is a non-GAAP financial measure) for each of the periods indicated. For additional information on these non-GAAP financial measures, see “Non-GAAP Financial Measures” above.

Cautionary Statement Regarding Forward-Looking Statements

This Form 12b-25 includes “forward-looking statements” within the meaning of the “safe harbor” provisions of the Private Securities Litigation Reform Act of 1995. The Company’s actual results may differ from their expectations, estimates and projections and consequently, you should not rely on these forward-looking statements as predictions of future events. Words such as “expect,” “estimate,” “anticipate,” “intend,” “plan,” “may,” “will,” “could,” “should,” “believes,” “continue,” and similar expressions are intended to identify such forward-looking statements. These forward-looking statements include, without limitation, the timing of the filing of its Quarterly Report on Form 10-Q for the fiscal quarter ended September 30, 2021. These forward-looking statements involve significant risks and uncertainties that could cause the actual results to differ materially from the expected results, including those discussed in our amended S-1 registration statement filed with the SEC on July 28, 2021 under the heading “Risk Factors,” and other documents filed, or to be filed, by ATI with the SEC. Most of these factors are outside the Company’s control and are difficult to predict. The Company cautions readers not to place undue reliance upon any forward-looking statements, which speak only as of the date made. The Company does not undertake or accept any obligation or undertaking to release publicly any updates or revisions to any forward-looking statements to reflect any change in its expectations or any change in events, conditions or circumstances on which any such statement is based.

ATI Physical Therapy, Inc.

(Name of Registrant as Specified in Charter)

has caused this notification to be signed on its behalf by the undersigned hereunto duly authorized.

INSTRUCTION: The form may be signed by an executive officer of the registrant or by any other duly authorized representative. The name and title of the person signing the form shall be typed or printed beneath the signature. If the statement is signed on behalf of the registrant by an authorized representative (other than an executive officer), evidence of the representative’s authority to sign on behalf of the registrant shall be filed with the form.