Apple and its iPhone and App Store business have been eyed by the Department of Justice, which previously filed antitrust suits against Google.

A bipartisan group of lawmakers is pushing for a piece of financial reform that would unshackle small businesses and consumers alike from the maw of Visa and Mastercard’s credit card duopoly. Wall Street, in response, is spending millions to thwart the bill’s recent advances by fueling a conservative culture war over gay...