Sears shares have been falling in recent days, closing yesterday at $153.13, down from a peak of $163.50 on July 20.
Even after a recent correction, Sears shares are still up more than 40 percent this year.
The buyback, which will take place over an unspecified time, represents about 9 percent of the outstanding Sears shares.
The trust controls 51.5 million Sears shares, or 15 percent of the total.
Sears shares closed at $45.50 yesterday, up 12.5 cents in trading on the New York Stock Exchange.
The price of a Sears share fell 37.5 cents today, to $34.25, on the New York Stock Exchange.
At the end of last year, a Kmart share sold for almost exactly half the price of a Sears share.
Only one has a "buy" recommendation, seven have "holds" on the stock, and four are recommending the sale of Sears shares.
Sears shares fell 25 cents, to $44.625.
Mr. Lacy would receive about $23.2 million from his options if the value of the deal was $50 a Sears share.
