"The return on net buyback cost is negative in every year except 2016. The cumulative return for each year is negative relative to the current share price."
https://seekingalpha.com/article/4102062-capital-allocation-review-dividends-buybacks-ibm-intel-microsoft
IBM notes:
Buyback program did not appear to impact dividend growth.
The number of shares purchased in 2012-2014 was much higher than seen in 2015. Poor execution of overall program to buy less when prices are relatively lower.
The return on net buyback cost is negative in every year except 2016. The cumulative return for each year is negative relative to the current share price.
The balance sheet at calendar year 2011 shows net cash (cash less debt) of ($19)B and equity of $20B. The balance sheet as of June 30, 2017 has net cash of $(33)B and equity of $18B. Conclusion: IBM has seen a modest deterioration of capital structure during period covered.