By Jon Kamp Of DOW JONES NEWSWIRES Pharmacy-benefit managers Express Scripts Inc. (ESRX) and Medco Health Solutions Inc. (MHS) said they are working with the Federal Trade Commission to secure approval for their planned deal, which could close within a matter of weeks. Express Scripts is planning to buy Medco--in a cash-and-stock deal valued at $29 billion when it was announced in July--to create the industry's biggest firm. Pharmacy-benefit managers, or PBMs, handle drug benefits for corporations and health plans. The companies certified on Feb. 10 that they had complied with the FTC's requests, setting a 30-day clock for the agency to complete its antitrust review, unless the parties agreed to allow more time. While that clock expired Monday, the two PBMS said they have agreed with the FTC not to close the deal yet. "Medco and Express Scripts continue to work with the FTC and expect that the mergers will be completed by the earlier part of the second quarter of 2012," the companies said in filings with the Securities and Exchange Commission, made late Monday. Express Scripts shares climbed 1.5% to $54.25 in after-hours trading, while Medco shares rose 0.6% to $68.75. The spread between the planned purchase price and Medco's stock has narrowed in recent days--it was about 5.5% after Monday's close--amid signs the deal could be closer to gaining approval. Several trade groups and consumer advocates have urged the FTC to block the deal. But The Wall Street Journal reported Friday that the agency appears increasingly unlikely to do so. The FTC still has some concerns about the combination, and talks were under way to resolve them, the WSJ reported, citing people familiar with the matter. -By Jon Kamp, Dow Jones Newswires; 617-654-6728; firstname.lastname@example.org --Brent Kendall contributed to this article.