FRAMINGHAM, Mass. (AP) — Staples and Office Depot are planning to extend the deadline to get their business combination done.

The office supply companies said Wednesday that the extension allows for the completion of ongoing federal district court litigation with the Federal Trade Commission.

Last month federal regulators rejected an offer from Staples to sell $1.25 billion in contracts, an attempt on the part of the retailer to ease monopoly fears as it tries to acquire rival Office Depot for $6.3 billion. The Federal Trade Commission sought to block the deal in early December, saying that a tie up between the last of the major office supply retailers would throttle competition in the sector. Regulators have said that competition between the two is crucial to keep prices fair for those industries that must acquire pens, paper and other supplies.

Staples Inc. and Office Depot Inc. have agreed to extend the deadline for their deal from Feb. 4 to May 16. The companies are working to extend financing terms for the transaction.

Staples is based in Framingham, Massachusetts. Office Depot is based in Boca Raton, Florida.

Staples shares fell 48 cents, or 5.4 percent, to $8.34, while Office Depot shares lost 13 cents, or 2.6 percent, to $4.91 in afternoon trading amid a broad selloff.