five-year performance comparison 2013 the following graph provides an indicator of cumulative total shareholder returns for the corporation as compared to the peer group index ( described above ) , the dj trans , and the s&p 500 . the graph assumes that $ 100 was invested in the common stock of union pacific corporation and each index on december 31 , 2010 and that all dividends were reinvested . the information below is historical in nature and is not necessarily indicative of future performance . purchases of equity securities 2013 during 2015 , we repurchased 36921641 shares of our common stock at an average price of $ 99.16 . the following table presents common stock repurchases during each month for the fourth quarter of 2015 : period total number of shares purchased [a] average price paid per share total number of shares purchased as part of a publicly announced plan or program [b] maximum number of shares remaining under the plan or program [b] .
[a] total number of shares purchased during the quarter includes approximately 32086 shares delivered or attested to upc by employees to pay stock option exercise prices , satisfy excess tax withholding obligations for stock option exercises or vesting of retention units , and pay withholding obligations for vesting of retention shares . [b] effective january 1 , 2014 , our board of directors authorized the repurchase of up to 120 million shares of our common stock by december 31 , 2017 . these repurchases may be made on the open market or through other transactions . our management has sole discretion with respect to determining the timing and amount of these transactions. .
Period Total Number of Shares Purchased [a] Average Price Paid Per Share Total Number of Shares Purchased as Part of a Publicly AnnouncedPlan or Program [b] Maximum Number of Shares Remaining Under the Plan or Program [b]
Oct. 1 through Oct. 31 3,247,731 $92.98 3,221,153 56,078,192
Nov. 1 through Nov. 30 2,325,865 86.61 2,322,992 53,755,200
Dec. 1 through Dec. 31 1,105,389 77.63 1,102,754 52,652,446
Total 6,678,985 $88.22 6,646,899 N/A
period total number of shares purchased [a] average price paid per share total number of shares purchased as part of a publicly announcedplan or program [b] maximum number of shares remaining under the plan or program [b]
oct . 1 through oct . 31 3247731 $ 92.98 3221153 56078192
nov . 1 through nov . 30 2325865 86.61 2322992 53755200
dec . 1 through dec . 31 1105389 77.63 1102754 52652446
total 6678985 $ 88.22 6646899 n/a