The pitcher's contract calls for a $30 million signing bonus, of which $15 million is due by April 1, a person familiar with the agreement told The Associated Press on Sunday. The person spoke on condition of anonymity because those details have not been announced.
The previous high for a signing bonus had been Vernon Wells' $25.5 million under a $126 million, seven-year deal with Toronto that covered 2008-14 and was announced in December 2006. Wells' bonus was payable in three equal installments on March 1 each year from 2008-10.
Lester's upfront payment tops a mark set Dec. 8 by Cuban defector Yasmany Tomas. The Arizona Diamondbacks agreed to a $14 million signing bonus for the Cuban outfielder-third baseman, all payable within 30 days of the deal's approval by Major League Baseball.
Tomas broke a record that had stood since January 1993, when Cecil Fielder agreed to a $36 million, five-year contract with Detroit that included an upfront signing bonus of $10,187,500.
Chicago and Lester spread out the rest of the signing bonus in three stages, with $2.5 million payments due by Dec. 31 in 2018 and 2019, and a final $10 million installment by Sept. 15, 2020.
Lester's contract was agreed to last Tuesday at the winter meetings by the Cubs and agents Sam and Seth Levinson. The Cubs said Saturday they will introduce Lester on Monday at Spiaggia Restaurant, a favorite of President Barack Obama and his family.
Lester's deal includes an option for 2021 that, if it becomes guaranteed, would make the deal worth $170 million over seven seasons.
A three-time All-Star who turns 31 next month, Lester helped Boston win World Series titles in 2007 and `13. He was dealt by the Red Sox to Oakland at the trade deadline in July and helped the Athletics reach the playoffs.
Lester was 16-11 with a career-best 2.46 ERA and 220 strikeouts this year. He is 116-67 with a 3.58 ERA in nine big league seasons.