On October 2, 2014, the Company acquired all of the outstanding shares of Western World. The acquisition provided the Company with enhanced access to the specialty U.S. commercial insurance market, the world's largest short-tail market, complementing the Company's existing market positions in both Bermuda reinsurance and the Lloyd's marketplace and increasing the Company's ability to leverage operational strengths in short-tail classes of business. In addition, the acquisition improves the Company's ability to manage (re)insurance cycles.
Book value per diluted common share plus accumulated dividends is calculated based on total shareholders’ equity available to Validus plus the assumed proceeds from the exercise of outstanding options and warrants, divided by the sum of common shares, unvested restricted shares and options and warrants outstanding (assuming their exercise), plus accumulated dividends. Book value per diluted common share plus accumulated dividends is a non-GAAP financial measure, which are described in the section entitled “Non-GAAP Financial Measures.”
Combined ratio for the year ended December 31, 2015 was 79.7% which included $306.1 million of favorable loss reserve development on prior accident years, benefiting the loss ratio by 13.6 percentage points compared to a combined ratio for the year ended December 31, 2014 of 73.6% which included $259.2 million of favorable loss reserve development on prior accident years, benefiting the loss ratio by 13.0 percentage points.
The property lines current period loss ratio, excluding the impact of notable and non-notable loss events, decreased by 11.5 percentage points as a result of lower attritional losses in the current year and a construction fire loss of $8.3 million included in the year ended December 31, 2014. The favorable development of $52.4 million on prior accident years for the year ended December 31, 2015 primarily relates to favorable development on attritional losses and certain events, including the Thailand floods, which was a 2011 notable loss event. The favorable development of $53.8 million on prior accident years for the year ended December 31, 2014 primarily relates to a combination of favorable development on attritional losses and notable loss events, primarily the Tohoku earthquake, which was a 2011 notable loss event.
Upon closing the acquisition, an adjustment of $15,586 was made to increase net reserves to reflect fair value. This adjustment was fully amortized to income through a reduction in losses and loss expenses of $10,979 during the year ended December 31, 2015 (2014: $4,607), benefiting the loss ratio by 4.2 percentage points (2014: 6.3 percentage points).
The property lines current period loss ratio was 66.1% percentage points, representing attritional claims experienced during the year. The favorable development of $6.0 million on prior accident years for the year ended December 31, 2015 primarily relates to favorable development on attritional losses.
Share compensation expenses for the three months ended December 31, 2015 were $3.5 million compared to $3.0 million for the three months ended December 31, 2014, an increase of $0.5 million or 17.1%.
The following table presents non-segment income and expense items on a consolidated basis for the years ended December 31, 2015, 2014 and 2013: