1. This transaction was executed in multiple trades at prices ranging from $144.00 to $144.05. The price reported above reflects the weighted average sale price. The reporting person hereby undertakes to provide upon request to the SEC staff, Illinois Tool Works Inc. or a shareholder of Illinois Tool Works Inc. full information regarding the number of shares and prices at which the transaction was effected.

2. Shares of common stock allocated to my account in the Illinois Tool Works Inc. Savings & Investment Plan--Information reported as of June 5, 2017.

3. Options vest in four (4) equal annual installments beginning one year from date of grant.

4. Each performance restricted stock unit (PRSU) and performance share unit (PSU) represents a contingent right to receive one share of the Company's common stock.

5. Each PRSU and PSU vests 100% three years from the date of grant if performance goals are met.