Ahead of an expected lifting of sanctions, several U.S. corporate giants including personal-computer seller HP Inc. HPQ 0.77 % and General Electric Inc.’s oil-services unit are actively exploring a market entry into Iran. U.S. companies other than food, aircraft-parts and medicine suppliers are still banned from conducting direct transactions with Iran. But last week Maryland Sen. Ben Cardin, the top Democrat on the Senate Foreign Relations Committee, said at a hearing that sanctions relief on Tehran could start in January , when an agreement with world powers over Iran’s controversial nuclear program is implemented. On the nuclear agreement’s “implementation day,” the U.S. Treasury’s Office of Foreign Assets Control will issue a general license authorizing foreign-based arms of U.S. corporations to engage in activities involving Iran, a U.S. official said. Worried they could be left behind their European and Asian peers in the race to do business with a country […]