Staples Inc. chief executive Ron Sargent saw his pay package drop in value by 20 percent in 2015, during a year when he engineered the troubled deal to buy the Framingham company’s largest rival, Office Depot Inc.

Sargent’s total compensation of $9.9 million was about $2.5 million less than his 2014 package because he didn’t receive any cash incentive award last year, according to documents the company filed with the US Securities and Exchange Commission Tuesday. Sargent was eligible for a cash incentive award in 2015 of $620,000 but opted to forego it. He was the only one of Staples’ top five executives to not get a cash incentive for 2015.

A spokesman said Sargent volunteered to give up the incentive to “be aligned with shareholder performance for 2015.’’ Sargent, the spokesman said, also declined a pay increase for the second year in a row. His base salary remained $1.25 million.

Staples has been trying to right its business in the face of increased competition from online retailers. During its most recent fiscal year, total revenue fell 6.4 percent, to $21 billion. And its shares plunged from the $18 range at the end of 2014 to around $9.50 at the end of last year. The stock closed at $10.64 a share on Tuesday.

The company’s would-be partner, Office Depot, is also facing declining sales, and both companies are closing stores.

And their deal to join forces remains in doubt: The Federal Trade Commission has moved to block the acquisition, valued at $6 billion when it was announced in February 2015. That challenge is being reviewed by a federal judge in Washington, D.C., with a decision expected by mid-May.

The FTC claims the combination would hurt competition for large business supply contracts. Sargent and his team argue that the merger would help the combined company offer those corporate customers better prices.

Still, Staples reported awarding Sargent the same amount of stock in 2015 as in the previous year: $8.2 million, based on the value of those shares as of March 2015. However, to receive all those shares, the spokesman said, Sargent needs to remain with the company for three years and hit certain performance benchmarks.

Jon Chesto can be reached at jon.chesto@globe.com. Follow him on Twitter @jonchesto.