SFM Holdings, Ltd. appeals the dismissal with prejudice of its complaint seeking damages for breach of fiduciary duty and constructive fraud. For the reasons set forth below, we affirm the judgment of the district court.
I. Facts and Procedural History
Appellant SFM Holdings, Ltd. (“SFM”) is one of 178 investors defrauded in one of the largest securities fraud cases in Florida history. The perpetrators, John Kim and Won Lee, operated as investment advisers using various entities, including Shoreland Trading. Dr. Salomon Melgen is the president and general partner of SFM. John Kim convinced Dr. Melgen to set up a brokerage account with Banc of America Securities, LLC. (Compl. ¶ 14).1 Dr. Melgen never had any direct contact with Banc of America Securities or its employees. When the account was set up, Dr. Melgen ceded a “limited” power of attorney to trade securities in the Banc of America Securities prime brokerage account. {Id. ¶¶ 14-17). Two of the documents completed to open the account were the Prime Broker Margin Account Agreement (“PB Agreement”) and the Institutional Account Agreement (“LA Agreement”). The PB Agreement clearly and plainly stated that Banc of America Securities — referred to in the agreement as BofA — was not an adviser or fiduciary.
Customer acknowledges that none of the BofA Entities or their respective agents or affiliates is acting as a fiduciary for or an adviser to Customer in respect of this Agreement or any transaction it may undertake with the BofA Entities; Customer understands that the BofA Entities are not acting as investment advisers or soliciting orders, that the BofA Entities are not advising it, performing any analysis, or making any judgment on any matters pertaining to the suitability of any order, or offer any opinion, judgment or other type of information pertaining to the nature, value, poten*1336tial, or suitability of any particular invest[ment].
(Appellee’s Br., Ex. A, ¶ 11(b)). The IA Agreement established Banc of America Securities as SFM’s “agent for the purposes of buying and selling securities.” (Appellee’s Br., Ex. B, ¶ 3).
On September 28, 2004, SFM put $10 million into the account with Banc of America Securities. Soon thereafter another'$2.3 million was put into the account. (Compl. ¶ 22). Within a month, SFM was losing money in the account, and Dr. Mel-gen told John Kim that he wanted to close the account. (Id. ¶ 23). In response, Kim convinced Dr. Melgen to leave his money in the account in exchange for a written guarantee of his principal by Kim and Shoreland Trading. (Id. ¶ 24). Won Lee was also a partner with Kim in Shoreland. The complaint alleges that Won Lee had been trading extensively in SFM’s account. Shortly thereafter, Lee attempted to make an illegal trade — selling a large amount of stock short without arranging to borrow the stock first — in the account. (Compl. ¶ 42). Upon discovering the illegal trade the next day, Banc of America Securities ordered Lee to cover the short sale. The next day, Kim or Lee repeated the illegal short sale. Banc of America Securities then ordered Lee to remove all of his accounts (including SFM’s) from Banc of America Securities. (Compl. ¶ 45). Nevertheless, Banc of America Securities permitted Lee and Shoreland to trade in the account for more than four weeks. (Compl. ¶ 47). According to the complaint, Banc of America Securities never notified Dr. Melgen of any suspicious trading activity in the account. (Compl. ¶ 51).
On November 2, 2004, Banc of America Securities received a letter signed by Dr. Melgen directing it to transfer SFM’s assets to Shoreland’s account. Dr. Melgen now claims that letter was a forgery. On the same day, Won Lee wrote Banc of America Securities confirming that he would accept SFM’s assets into Shore-land’s account with Banc of America Securities. Within two weeks, Shoreland transferred the money to another company, Wedbush Morgan Securities, LLC. This account was in the name of Shoreland only. (Compl. ¶ 29). All of the money was then stolen or lost in disastrous trading.
SFM filed this action against Banc of America Securities, claiming damages due to violations of federal and state securities laws, breach of fiduciary duty, and constructive fraud.2 On the Defendant’s motion, the district court dismissed the claims with prejudice. SFM appeals the dismissal of the breach of fiduciary duty and constructive fraud claims.
II. Jurisdiction and Standard of Review
We have jurisdiction over the appeals of final decisions of the district court pursuant to 28 U.S.C. § 1291. We exercise de novo review as to the district court’s decision to grant a motion to dismiss. Cachia v. Islamorada, 542 F.3d 839, 841-42 (11th Cir.2008). We review the district court’s refusal to grant leave to amend for abuse of discretion, although we exercise de novo review as to the underlying legal conclusion that an amendment to the complaint would be futile. Harris v. Ivax Corp., 182 F.3d 799, 802 (11th Cir.1999).
*1337III. Discussion
A.
First, SFM argues that the district court erred in converting the Defendant’s Rule 12(b)(6) motion to dismiss into a motion for summary judgment without giving notice to the Plaintiff. Reading the Order of the district court, it is clear that the court did not do that. The district court did, however, consider and rely upon the PB Agreement in granting the Defendant’s motion to dismiss. According to SFM, consideration of the document converted the Rule 12(b)(6) motion to dismiss into a Rule 56 motion for summary judgment, which would have required notice of the conversion to the parties. SFM claims it was prejudiced by the lack of notice and the lack of opportunity for discovery.
The Defendant argues that the district court’s consideration of the PB Agreement was proper because the document was incorporated by reference into the complaint and the document was central to the Plaintiffs claim. In general, if it considers materials outside of the complaint, a district court must convert the motion to dismiss into a summary judgment motion. See Fed.R.Civ.P. 12(b). There is an exception, however, to this general rule. In ruling upon a motion to dismiss, the district court may consider an extrinsic document if it is (1) central to the plaintiffs claim, and (2) its authenticity is not challenged. Day v. Taylor, 400 F.3d 1272, 1276 (11th Cir.2005); see also Maxcess, Inc. v. Lucent Technologies, Inc., 433 F.3d 1337, 1340 (11th Cir.2005) (“a document outside the four corners of the complaint may still be considered if it is central to the plaintiffs claims and is undisputed in terms of authenticity.”). SFM does not dispute the authenticity of the PB Agreement. It does argue that the document was not incorporated by reference into the complaint and that, even if it was, the document was not central to its claims.
Although the PB Agreement was not attached to the complaint, the complaint noted that the brokerage account was opened by “documents provided to John Kim and Won Lee by Banc of America Securities.” (Compl. ¶ 18). These documents were repeatedly described as “account opening documents.” (Id.) SFM does not deny that the PB Agreement is one of the account opening documents mentioned in the complaint. The Defendant argues that the agreement was the account opening document that established Banc of America Securities as a prime broker .for SFM and absolved Banc of America Securities from any fiduciary duty as to the account. According to SFM, another document, the IA Agreement, established Banc of America Securities as its executing broker. Under SFM’s theory, Banc of America Securities’s role as an executing broker imposes upon it a fiduciary duty. However, there is no doubt that the PB Agreement determined the terms of the relationship between SFM and Banc of America Securities. The agreement set forth the “terms and conditions” on which Banc of America Securities will “open and maintain accounts for and otherwise transact business with the customer .... ” (Appellee’s Br., Ex. A at 1). Further, to the extent that the terms of the PB Agreement conflicted with another agreement, it stated that it controlled over any other agreements between Banc of America Securities and its customer. (Appellee’s Br., Ex. A ¶ 20). We have previously held that such relationship-forming contracts are central to a plaintiffs claim. Maxcess, 433 F.3d at 1340 n. 3. The district court did not err in considering the PB Agreement in ruling on the motion to dismiss.
In its briefing on appeal, SFM relies on the other account opening docu*1338ment, the IA Agreement, to argue that Banc of America Securities had a fiduciary duty. Specifically, SFM argues that such a duty was established because the IA Agreement made Banc of America Securities its “agent for the purposes of buying and selling securities.” (Appellee’s Br., Ex. B, ¶ 3). The Defendant argues that SFM never relied on the IA Agreement to establish an agency in the district court proceedings, and that it cannot do so now. See, e.g., Access Now, Inc. v. Southwest Airlines Co., 385 F.3d 1324, 1331 (11th Cir.2004) (“This Court has repeatedly held that an issue not raised in the district court and raised for the first time in an appeal will not be considered by this court.”) (citations omitted). In this case, SFM did not waive this argument. Rather, it made its agency argument relying on the PB Agreement, which the Defendant acknowledges “contained nearly identical language.” (Appellee’s Br. at 35, n. 11). Further, the IA Agreement was already in the record, albeit for purposes of opposing the Defendant’s motion to transfer venue. SFM put the IA agreement in the record before the district court, and it now asserts that the IA agreement is one of the account opening documents, which are central to its claim. Also, as we have already explained, the PB Agreement sets the terms of the parties’ relationship, even when considered alongside of the IA agreement. For these narrow reasons, and for the sake of completeness, we will consider that document on appeal along with the PB agreement as one of the account opening documents.
B.
SFM argues that the dismissal of its claims was improper because it alleged that Banc of America Securities was an executing broker in addition to a prime broker. The Defendant does not deny that it may have been both. “Banc of America Securities was engaged as a prime and executing broker.” (Appellee’s Br. at 14). Traditionally, executing brokers (distinct from the prime broker) take, or execute, trades in direct communication with the customer. The prime broker’s role is usually ministerial — it allows the customer to open an account with it, and allows the executing broker to make trades for the benefit of the customer in the prime broker’s name. See Practicing Law Institute, The SEC Speaks in 2000: Mateñals Submitted by the Division of Investment Management, 1169 PLI/Corp 383, 642-43 (2000 Practicing Law Institute) (“The client or its fiduciary closes the short position by notifying [the prime broker] that it has placed a covering transaction. The client covers the transaction by purchasing securities through an executing broker who confirms the trade with [the prime broker, who] then clears and settles the transaction.”). Banc of America Securities claims that “[ojften, prime brokers execute transactions as well.” (Appellee’s Br. at 14). To clear up this confusion, Banc of America Securities argues that it was not an “introducing broker.” An introducing broker is usually the one who advises the customer and exercises discretion over its prime brokerage account.
SFM does not specifically allege that Banc of America Securities acted as an introducing broker. SFM does argue, however, that the terms “prime broker” and “clearing broker” are interchangeable, both performing ministerial services for executing and introducing brokers, respectively. Generally, clearing brokers execute, clear, and settle trades for the introducing brokers who have direct relationships with the client. Stuart J. Kaswell & Daniele Marchesani, The ABCs of Broker-Dealer Regulation 2007: Broker-Dealer Regulation — An Overview, 1604 PLI/Corp 9, 12 (2007 Practicing Law Institute). Like prime brokers, clearing *1339brokers ordinarily owe no fiduciary duty to the customers of introducing brokers. Strategic Income Fund, LLC v. Spear, Leeds & Kellogg Corp., 305 F.3d 1293, 1296 n. 12 (11th Cir.2002).
SFM suggests that Banc of America Securities’s characterization of its role reflects a fundamental misunderstanding of traditional prime brokerage arrangements.3 To resolve this dispute over terminology, we examine a Securities and Exchange Commission No-Action Letter (“No-Action Letter”) discussing the nature of the prime brokerage industry. See Prime Broker Committee Request, SEC No-Action Letter, 1994 WL 808441 (January 25, 1994). By its terms, the PB Agreement is subject to the No-Action Letter. (Appellee’s Br., Ex. A, ¶ 2). As described in the No-Action Letter, the customer, prime broker, and executing broker are typically “distinct parties.” (No-Action Letter at *1). Usually, “the executing broker takes the order from the customer, yet the prime broker typically issues the confirmation [of the order].” {Id. at *5). Nevertheless, the No-Action Letter does predict variations on this model. Some brokers may act “as executing brokers who clear prime broker transactions.” (Id. at *7). And, “the clearing firm of an introducing broker acting as an executing broker” must execute a prime brokerage contract listing the responsibilities of the parties. {Id. at *8). Moreover, the No-Action Letter contemplates a distinction between an executing broker and an introducing broker. (Id. at *8) (“In cases involving introducing broker-dealers who act as executing brokers, the executing broker must inform each broker-dealer dealing its transactions that it intends to act as an executing broker.”).
These distinctions may have significance in the regulatory context that are absent here. Whether Banc of America Securities had a fiduciary duty to SFM is determined by the substantive agreement of the parties. It is not determined by labels placed on the relationship. Kim, Lee and Shoreland acted as SFM’s investment ad-visor. Kim exercised discretionary control over the account according to the allegations of the complaint. The PB Agreement explicitly stated the Banc of America Securities was not acting as an adviser or fiduciary to the customer. It had no direct contact with SFM. Given this relationship, the fiduciary is the party who has direct contact with and provides investment advice to the customer. See McDaniel v. Bear Stearns & Co., 196 F.Supp.2d 343, 353 (S.D.N.Y.2002) (clearing firms only liable when they become “actively and directly involved in the introductory broker’s actions” and not when performing mere “routine clearing functions.”). Even if Banc of America Securities actually served as the prime and executing broker, “[i]n no way, shape or form does the complaint plead that [Banc of America Securities] was making decisions regarding the accounts [but rather] simply executed the [SFM] transactions along with the other transactions sent to it by [Kim].” Dillon v. Militano, 731 F.Supp. 634, 636 (S.D.N.Y.1990).
SFM argues that the IA Agreement created a fiduciary duty with this language: “Client appoints Banc of America Securities as its agent for the purposes of buying and selling securities in its Cash Account.” (Appellee’s Br., Ex. B, ¶ 3). As part of that agency, the agreement authorized Banc of America Securities to “act upon client’s instructions or those of its attor*1340ney-in-fact.” (Id.) Under SFM’s theory, that agency created a fiduciary duty, even though the same provision in the agreement states that Banc of America Securities “shall incur no liability in acting upon any such instructions ... provided such instructions reasonably appear genuine to Bane of America Securities.” (Id.) The IA Agreement, standing alone, did not create a fiduciary duty of Bane of America Securities to SFM. See Limbaugh v. Merrill Lynch, Pierce, Fenner & Smith, 732 F.2d 859, 862 (11th Cir.1984) (no liability where broker discharged its limited duty of executing stock orders). Any actions Banc of America Securities performed at the behest of Kim were authorized by the IA Agreement. Further, even supposing that Won Lee forged a letter to transfer Dr. Melgen’s funds into Shoreland’s account (this is disputed), the agreement authorized Banc of America Securities to act upon any client instructions that “reasonably appeared] genuine.” (Id.) Therefore, Banc of America Securities’s actions were appropriate within the limited agency created by the IA Agreement. Significantly, the agreement provided that Banc of America Securities could accept “without any inquiry or investigation by Banc of America Securities ... any other instructions concerning said Account” from an introducing broker. (Appellee’s Br., Ex. B, ¶ 27).
SFM argues that Shoreland was not an introducing broker in this relationship, but only a mere adviser. The argument must fail. First, Shoreland was registered as a broker-dealer with the Securities and Exchange Commission until its registration was revoked in 2007. Shoreland Trading, LLC, 24 S.E.C. Release No. 55688, 2007 WL 1285754 (May 1, 2007). Further, the IA Agreement defines an introducing broker as “another broker through whose courtesy Client’s Account has been introduced.” (Appellee’s Br., Ex. B, ¶ 27). There is no dispute that Shoreland (acting through its representatives) set up the prime brokerage account. Shoreland was acting as an introducing broker for SFM. Finally, the complaint acknowledges that Lee controlled Shoreland Trading. (Compl. ¶ 12). Paragraph 27 of the IA Agreement absolves Banc of America Securities of liability for the acts and omissions of the introducing broker’s officers, employees, or agents. (Appellee’s Br., Ex. B, ¶ 27). Banc of America Securities performed to the extent of the agency created in the IA Agreement. The complaint does not allege that Banc of America Securities failed to settle and clear all trades. SFM’s breach of fiduciary duty and construction fraud claims were properly dismissed.
We also find that the district court did not abuse its discretion in dismissing the complaint with prejudice. In its briefing on appeal, SFM seeks leave to amend because the factual allegations could support a breach of contract claim. However, as discussed above, Banc of America Securities acted pursuant to the IA Agreement and the PB Agreement. Banc of America Securities’s compliance with its obligations under those documents precludes liability for breach of contract. Therefore, the suggested amendment would be futile.
IV. Conclusion
For the reasons set forth above, the judgment of the district court is
AFFIRMED.