the company had net realized capital losses for 2015 of $ 184.1 million .in 2015 , the company recorded $ 102.2 million of other-than-temporary impairments on fixed maturity securities , $ 45.6 million of losses due to fair value re-measurements and $ 36.3 million of net realized capital losses from sales of fixed maturity and equity securities .in 2014 , net realized capital gains were $ 84.0 million due to $ 121.7 million of gains from fair value re-measurements on fixed maturity and equity securities and $ 1.9 million of net realized capital gains from sales of fixed maturity and equity securities , partially offset by $ 39.5 million of other-than- temporary impairments on fixed maturity securities .in 2013 , net realized capital gains were $ 300.2 million due to $ 258.9 million of gains due to fair value re-measurements on fixed maturity and equity securities and $ 42.4 million of net realized capital gains from sales of fixed maturity and equity securities , partially offset by $ 1.1 million of other-than-temporary impairments on fixed maturity securities .the company 2019s cash and invested assets totaled $ 17.7 billion at december 31 , 2015 , which consisted of 87.4% ( 87.4 % ) fixed maturities and cash , of which 91.4% ( 91.4 % ) were investment grade ; 8.2% ( 8.2 % ) equity securities and 4.4% ( 4.4 % ) other invested assets .the average maturity of fixed maturity securities was 4.1 years at december 31 , 2015 , and their overall duration was 3.0 years .as of december 31 , 2015 , the company did not have any direct investments in commercial real estate or direct commercial mortgages or any material holdings of derivative investments ( other than equity index put option contracts as discussed in item 8 , 201cfinancial statements and supplementary data 201d - note 4 of notes to consolidated financial statements ) or securities of issuers that are experiencing cash flow difficulty to an extent that the company 2019s management believes could threaten the issuer 2019s ability to meet debt service payments , except where other-than-temporary impairments have been recognized .the company 2019s investment portfolio includes structured commercial mortgage-backed securities ( 201ccmbs 201d ) with a book value of $ 264.9 million and a market value of $ 266.3 million .cmbs securities comprising more than 70% ( 70 % ) of the december 31 , 2015 market value are rated aaa by standard & poor 2019s financial services llc ( 201cstandard & poor 2019s 201d ) .furthermore , securities comprising more than 90% ( 90 % ) of the market value are rated investment grade by standard & poor 2019s .the following table reflects investment results for the company for the periods indicated: .
[['( dollars in millions )', 'december 31 , average investments ( 1 )', 'december 31 , pre-tax investment income ( 2 )', 'december 31 , pre-tax effective yield', 'december 31 , pre-tax realized net capital ( losses ) gains ( 3 )', 'december 31 , pre-tax unrealized net capital gains ( losses )'], ['2015', '$ 17430.8', '$ 473.8', '2.72% ( 2.72 % )', '$ -184.1 ( 184.1 )', '$ -194.0 ( 194.0 )'], ['2014', '16831.9', '530.6', '3.15% ( 3.15 % )', '84.0', '20.3'], ['2013', '16472.5', '548.5', '3.33% ( 3.33 % )', '300.2', '-467.2 ( 467.2 )'], ['2012', '16220.9', '600.2', '3.70% ( 3.70 % )', '164.4', '161.0'], ['2011', '15680.9', '620.0', '3.95% ( 3.95 % )', '6.9', '106.6']]
pre-tax pre-tax pre-tax pre-tax realized net unrealized net average investment effective capital ( losses ) capital gains ( dollars in millions ) investments ( 1 ) income ( 2 ) yield gains ( 3 ) ( losses ) 17430.8$ 473.8$ 2.72% ( 2.72 % ) ( 184.1 ) $ ( 194.0 ) $ 16831.9 530.6 3.15% ( 3.15 % ) 84.0 20.3 16472.5 548.5 3.33% ( 3.33 % ) 300.2 ( 467.2 ) 16220.9 600.2 3.70% ( 3.70 % ) 164.4 161.0 15680.9 620.0 3.95% ( 3.95 % ) 6.9 106.6 ( 1 ) average of the beginning and ending carrying values of investments and cash , less net funds held , future policy benefit reserve , and non-interest bearing cash .bonds , common stock and redeemable and non-redeemable preferred stocks are carried at market value .common stock which are actively managed are carried at fair value .( 2 ) after investment expenses , excluding realized net capital gains ( losses ) .( 3 ) included in 2015 , 2014 , 2013 , 2012 and 2011 are fair value re-measurements of ( $ 45.6 ) million , $ 121.7 million , $ 258.9 million , $ 118.1 million and ( $ 4.4 ) million , respectively. .

Question: what is the book to market ratio of the commercial mortgage-backed securities
Answer: 0.99
Explanation: the ratio of the commercial mortgage-backed securities is one to one