Stillwater Mining Company d/b/a Sibayne Stillwater Limited v. Prudential Retirement Insurance and Annuity Company and John Does 1–10

CourtDistrict Court, D. Montana
DecidedJune 8, 2026
Docket1:25-cv-00139
StatusUnknown

This text of Stillwater Mining Company d/b/a Sibayne Stillwater Limited v. Prudential Retirement Insurance and Annuity Company and John Does 1–10 (Stillwater Mining Company d/b/a Sibayne Stillwater Limited v. Prudential Retirement Insurance and Annuity Company and John Does 1–10) is published on Counsel Stack Legal Research, covering District Court, D. Montana primary law. Counsel Stack provides free access to over 12 million legal documents including statutes, case law, regulations, and constitutions.

Bluebook
Stillwater Mining Company d/b/a Sibayne Stillwater Limited v. Prudential Retirement Insurance and Annuity Company and John Does 1–10, (D. Mont. 2026).

Opinion

IN THE UNITED STATES DISTRICT COURT FOR THE DISTRICT OF MONTANA BILLINGS DIVISION

STILLWATER MINING COMPANY CV 25-139-BLG-TJC d/b/a SIBAYNE STILLWATER LIMITED, ORDER Plaintiff,

vs.

PRUDENTIAL RETIREMENT INSURANCE AND ANNUITY COMPANY and JOHN DOES 1–10,

Defendants.

This action was originally brought by Plaintiff Stillwater Mining Company d/b/a Sibayne Stillwater Limited (“Stillwater”) in the Montana Twenty-Second Judicial District Court, Stillwater County (DV-48-2025-0000063-OC) on September 29, 2025, against Defendant Prudential Retirement Insurance and Annuity Company (“Prudential”)1 and John Does 1–10. (Doc. 7.) Prudential timely removed the action to this Court, invoking diversity jurisdiction under 28 U.S.C. § 1332. (Doc. 1.) / / /

1 Prudential states that it is now legally known as Empower Annuity Insurance Company (Doc. 5 at 1); however, it has not moved to amend the case’s caption. Accordingly, and for the sake of clarity and simplicity, the Court will refer to Defendant as “Prudential”. Presently before the Court is Prudential’s motion to dismiss, pursuant to Federal Rule of Civil Procedure 12(b)(6). (Doc. 4.) The motion is fully briefed

and ripe for the Court’s review. (See Docs. 5, 11, 15.) For the following reasons, the Court finds Prudential’s motion should be GRANTED in part and DENIED in part.

I. BACKGROUND When considering a motion to dismiss under Rule 12(b)(6), a court must accept all material allegations in the complaint as true. Usher v. City of Los Angeles, 828 F.2d 556, 561 (9th Cir. 1987). The following facts are taken from

Stillwater’s Complaint (Doc. 7). Stillwater operates mines and related facilities in Montana. It employs, and has employed, thousands of Montanans in its operations. Stillwater maintains an

employer-sponsored, defined-contribution 401(k) retirement plan (“the Plan”) for its non-union employees. In 2014, Stillwater moved management of the Plan from Massachusetts Mutual Life Insurance Company to Prudential and its affiliates. Stillwater entered

into a Services Agreement (“the Agreement”) as well as a Trust Agreement and Investment Agreement with Prudential and its affiliates. The Agreement outlines services that Prudential would provide to Stillwater, including mapping

Stillwater’s old plan to Prudential’s prototype or specimen, providing notices to Stillwater and Plan participants, and providing various other documents regarding the Plan to Stillwater.

Despite holding itself out as an expert in the management of retirement plans of this kind, Stillwater alleges Prudential failed to properly map the Plan. Stillwater further alleges Prudential actively and intentionally concealed this fact

by providing Stillwater with inaccurate documentation. Stillwater claims Prudential’s actions necessitated Stillwater to, among other things, make “true-up” contributions as well as increased and unnecessary tax payments to keep the Plan in compliance.

Stillwater’s Complaint presents four causes of action: breach of contract (Count I); negligence (Count II); negligent misrepresentation (Count III); and breach of the implied covenant of good faith and fair dealing (Count IV).

II. LEGAL STANDARD “Dismissal under Rule 12(b)(6) is proper only when the complaint either (1) lacks a cognizable legal theory or (2) fails to allege sufficient facts to support a cognizable legal theory.” Li v. Kerry, 710 F.3d 995, 999 (9th Cir. 2013). The

Court’s standard of review under Rule 12(b)(6) is informed by Rule 8(a)(2), which requires that a pleading contain a “short and plain statement of the claim showing that the pleader is entitled to relief.” Ashcroft v. Iqbal, 556 U.S. 662, 677–78

(2009) (quoting Fed. R. Civ. P. 8(a)(2)). To survive a motion to dismiss under Rule 12(b)(6), “a complaint must contain sufficient factual matter, accepted as true, to state a claim to relief that is

plausible on its face.” Id. at 678 (internal quotation marks omitted). “A claim has facial plausibility when the plaintiff pleads factual content that allows the court to draw the reasonable inference that the defendant is liable for the misconduct

alleged.” Id. A plausibility determination is context-specific, and courts must draw on judicial experience and common sense in evaluating a complaint. Levitt v. Yelp! Inc., 765 F.3d 1123, 1135 (9th Cir. 2014). A court considering a Rule 12(b)(6) motion must accept as true the

allegations of the complaint and must construe those allegations in the light most favorable to the nonmoving party. See, e.g., Wyler Summit P’ship v. Turner Broad. Sys., Inc., 135 F.3d 658, 661 (9th Cir. 1998). Nevertheless, “bare assertions

. . . amount[ing] to nothing more than a ‘formulaic recitation of the elements’ . . . for the purposes of ruling on a motion to dismiss, are not entitled to an assumption of truth.” Moss v. U.S. Secret Serv., 572 F.3d 962, 969 (9th Cir. 2009) (quoting Bell Atl. Corp. v. Twombly, 550 U.S. 544, 555 (2007)). Such assertions do nothing

more than state a legal conclusion, even if the conclusion is cast in the form of a factual allegation. Id. / / /

/ / / III. DISCUSSION A. Consideration of Materials Outside of the Pleadings

In general, a court cannot consider materials outside of the pleadings when deciding a motion to dismiss under Rule 12(b)(6) without converting the motion into one for summary judgment under Rule 56. Khoja v. Orexigen Therapeutics,

Inc., 899 F.3d 988, 998 (9th Cir. 2018). An exception to this general rule is the incorporation-by-reference doctrine, which provides that “[e]ven if a document is not attached to a complaint, it may be incorporated by reference into a complaint if the plaintiff refers extensively to the document or the document forms the basis of

the plaintiff’s claim.” United States v. Ritchie, 342 F.3d 903, 908 (9th Cir. 2003). See also Marder v. Lopez, 450 F.3d 445, 448 (9th Cir. 2006) (“A court may consider evidence on which the complaint ‘necessarily relies’ if: (1) the complaint

refers to the document; (2) the document is central to the plaintiff’s claim; and (3) no party questions the authenticity of the copy attached to the 12(b)(6) motion.”). “The defendant may offer such a document, and the district court may treat such a document as part of the complaint, and thus may assume that its contents are true

for purposes of a motion to dismiss under Rule 12(b)(6).” Ritchie, 342 F.3d at 908. Stillwater did not attach anything to its Complaint. Nevertheless, Stillwater’s Complaint refers extensively to the Agreement, and it is central to its

case. Prudential included portions of the Agreement as a 46-page attachment to its brief in support of its motion to dismiss. (Doc. 5-1.) In its response to Prudential’s motion, Stillwater also included portions of the Agreement as a 21-page

attachment. (Doc.

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Stillwater Mining Company d/b/a Sibayne Stillwater Limited v. Prudential Retirement Insurance and Annuity Company and John Does 1–10, Counsel Stack Legal Research, https://law.counselstack.com/opinion/stillwater-mining-company-dba-sibayne-stillwater-limited-v-prudential-mtd-2026.