Regarding the charges incurred this quarter, I'd like to take a minute to expand upon them. With respect to the real estate initiative, the business case will yield $111 million in benefits over the next 10 years as we consolidate our Montréal real estate. Associated with this initiative, approximately $4 million of additional charges related to accelerated amortization will occur in Q4. On the charges related to the Logica transaction, expect to see a growing level of charges in the upcoming quarters as we move beyond closing and into the integration period.
Looking at the balance sheet, our DSO was 49 days in Q3 compared to 52 days we posted for the year-ago quarter. The decrease is mainly due to the timing of payments. We generated a record $251.0 million of cash from our operating activities compared with $93.2 million in the same period last year. This was the result of the improvements in the DSO from last quarter and the timing of payments related to other working capital items. Over the last 12 months, we have generated $690.5 million or $2.50 -- $2.57 in cash per diluted share. During the quarter, we booked $1.5 billion in contract wins bringing the total bookings over the last 12 months to $5.1 billion for a book-to-bill ratio of 123%.
As usual, we continue to stress the importance of considering our performance on cash and bookings trends over a trailing 12-month period.
During the quarter, we reduced our debt by $152.5 million for a net debt of $633.4 million. That's down almost $300 million from the year-ago period. And our net debt to capitalization ratio was 19.4% having being reduced from a peak of 31% following the Stanley acquisition. At the end of the quarter, we had approximately $4.5 billion in committed liquidity. In the quarter, we acquired 453,000 shares of $9.4 million, an average price of $20.82. Under the current buyback program, which expires in February 2013, we can still purchase more than 21 million shares.