JUSTICE THOMAS delivered the opinion of the Court, except as to footnote 6. . . .

II

Respondents claim a right to judicial review of the NCUA’s chartering decision under §10(a) of the APA, which provides:

5 U.S.C. §702.

We have interpreted §10(a) of the APA to impose a prudential standing requirement in addition to the requirement, imposed by Article III of the Constitution, that a plaintiff have suffered a sufficient injury-in-fact. See, e.g., Association of Data Processing Service Organizations, Inc. v. Camp, 397 U.S. 150, 152 (1970) (Data Processing).

For a plaintiff to have prudential standing under the APA, "the interest sought to be protected by the complainant [must be] arguably within the zone of interests to be protected or regulated by the statute . . . in question." Id., at 153.

Based on four of our prior cases finding that competitors of financial institutions have standing to challenge agency action relaxing statutory restrictions on the activities of those institutions, we hold that respondents’ interest in limiting the markets that federal credit unions can serve is arguably within the zone of interests to be protected by §109. Therefore, respondents have prudential standing under the APA to challenge the NCUA’s interpretation. . . .

B

Our prior cases, therefore, have consistently held that for a plaintiff’s interests to be arguably within the "zone of interests" to be protected by a statute, there does not have to be an "indication of congressional purpose to benefit the would-be plaintiff." Id., at 399–400 (citing ICI); see also Arnold Tours, supra, at 46 (citing Data Processing). The proper inquiry is simply "whether the interest sought to be protected by the complainant is arguably within the zone of interests to be protected . . . by the statute." Data Processing, 397 U.S., at 153 (emphasis added). Hence in applying the "zone of interests" test, we do not ask whether, in enacting the statutory provision at issue, Congress specifically intended to benefit the plaintiff. Instead, we first discern the interests "arguably . . . to be protected" by the statutory provision at issue; we then inquire whether the plaintiff’s interests affected by the agency action in question are among them.

Section 109 provides that "[f]ederal credit union membership shall be limited to groups having a common bond of occupation or association, or to groups within a welldefined neighborhood, community, or rural district." 12 U.S.C. §1759. By its express terms, §109 limits membership in every federal credit union to members of definable "groups." Because federal credit unions may, as a general matter, offer banking services only to members, see, e.g., 12 U. S. C. §§1757(5)–(6), §109 also restricts the markets that every federal credit union can serve. Although these markets need not be small, they unquestionably are limited. The link between §109’s regulation of federal credit union membership and its limitation on the markets that federal credit unions can serve is unmistakable. Thus, even if it cannot be said that Congress had the specific purpose of benefiting commercial banks, one of the interests "arguably . . . to be protected" by §109 is an interest in limiting the markets that federal can serve. This interest is precisely the interest of respondents affected by the NCUA’s interpretation of §109. As competitors of federal credit unions, respondents certainly have an interest in limiting the markets that federal credit unions can serve, and the NCUA’s interpretation has affected that interest by allowing federal credit unions to increase their customer base.

Section 109 cannot be distinguished from the statutory provisions at issue in Clarke, ICI, Arnold Tours, and Data Processing. Although in Clarke the McFadden Act appeared to be designed to protect only the interest of state banks in parity of treatment with national banks, we nonetheless determined that the statute also limited "the extent to which [national] banks [could] engage in the discount brokerage business and hence limit[ed] the competitive impact on nonbank discount brokerage houses." Clarke, 479 U.S., at 403. Accordingly, although Congress did not intend specifically to protect securities dealers, one of the interests "arguably . . . to be protected" by the statute was an interest in restricting national bank market power. The plaintiff securities dealers, as competitors of national banks, had that interest, and that interest had been affected by the interpretation of the McFadden Act they sought to challenge, because that interpretation had allowed national banks to expand their activities and serve new customers. See ibid.

Similarly, in ICI, even though in enacting the GlassSteagall Act, Congress did not intend specifically to benefit investment companies and may have sought only to protect national banks and their depositors, one of the interests "arguably . . . to be protected" by the statute was an interest in restricting the ability of national banks to enter the securities business. The investment company plaintiffs, as competitors of national banks, had that interest, and that interest had been affected by the Comptroller’s interpretation allowing national banks to establish mutual funds.

So too, in Arnold Tours and Data Processing, although in enacting the National Bank Act and the Bank Service Corporation Act, Congress did not intend specifically to benefit travel agents and data processors and may have been concerned only with the safety and soundness of national banks, one of the interests "arguably . . . to be protected" by the statutes was an interest in preventing national banks from entering other businesses’ product markets. As competitors of national banks, travel agents and data processors had that interest, and that interest had been affected by the Comptroller’s interpretations opening their markets to national banks. See also NationsBank of N. C., N. A. v. Variable Annuity Life Ins. Co., 513 U.S. 251 (1995) (deciding that the Comptroller had permissibly interpreted 12 U.S.C. §24 Seventh to allow national banks to act as agents in the sale of annuities; insurance agents’ standing to challenge the interpretation not questioned). . . .

Respondents’ interest in limiting the markets that credit unions can serve is "arguably within the zone of interests to be protected" by §109. Under our precedents, it is irrelevant that in enacting the FCUA, Congress did not specifically intend to protect commercial banks. Although it is clear that respondents’ objectives in this action are not eleemosynary in nature, under our prior cases that too is beside the point.

III

Turning to the merits, we must judge the permissibility of the NCUA’s current interpretation of §109 by employing the analysis set forth in Chevron U. S. A. Inc. v. Natural Resources Defense Council, Inc., 467 U.S. 837 (1984). Under that analysis, we first ask whether Congress has "directly spoken to the precise question at issue. If the intent of Congress is clear, that is the end of the matter; for the court, as well as the agency, must give effect to the unambiguously expressed intent of Congress." Id., at 842843. If we determine that Congress has not directly spoken to the precise question at issue, we then inquire whether the agency’s interpretation is reasonable. See id., at 843–844. Because we conclude that Congress has made it clear that the same common bond of occupation must unite each member of an occupationally defined federal credit union, we hold that the NCUA’s contrary interpretation is impermissible under the first step of Chevron.

As noted, §109 requires that "[f]ederal credit union membership shall be limited to groups having a common bond of occupation or association, or to groups within a well-defined neighborhood, community, or rural district." Respondents contend that because §109 uses the article "a"—"i.e., one"—in conjunction with the noun "common bond," the "natural reading" of §109 is that all members in an occupationally defined federal credit union must be united by one common bond. See Brief for Respondents 33. Petitioners reply that because §109 uses the plural noun "groups," it permits multiple groups, each with its own common bond, to constitute a federal credit union. See Brief for Petitioner NCUA 29–30.