Mortgage-backed securities Amortized Cost (in millions of U. S.  dollars)
## Table 0 ##
Our mortgage-backed securities are rated predominantly AAA and comprise approximately 25 percent of our fixed income portfolio.
This compares with a 35 percent mortgage-backed weighting in representative indices of the U. S.  fixed income market at the end of the fourth quarter of 2010.
The minimum rating for our initial purchases of mortgage-backed securities is AAA.
Agency RMBS represent securities which have been issued by Federal agencies (Government National Mortgage Association, Federal National Mortgage Association, and Federal Home Loan Mortgage Corporation) with implied or explicit government guarantees.
These represent 89 percent of our total RMBS portfolio.
With respect to our non-agency RMBS, these are backed primarily by prime collateral and are broadly diversified in over 220,000 loans.
This portfolio’s loan-to-value ratio is approximately 70 percent with an average Fair Isaac Corporation (FICO) score of 730.
With this conservative loan-to-value ratio and subordinated collateral of 12 percent, the cumulative 5-year foreclosure rate would have to rise to 18 percent and real estate values would have to fall 19 percent from their levels at the end of the fourth quarter of 2010, before principal is impaired.
The foreclosure rate for ACE’s non-agency RMBS portfolio was nine percent at the end of the fourth quarter of 2010.
Our commercial mortgage-backed securities (CMBS) are rated predominantly AAA, broadly diversified with over 17,000 loans, and 79 percent of the portfolio was issued before 2006.
The average loan-to-value ratio is approximately 68 percent with a debt service coverage ratio in excess of 1.7 and weighted-average subordinated collateral of 33 percent.
The cumulative foreclosure rate would have to rise to 41 percent and commercial real estate values would have to fall more than five percent from their levels at the end of the fourth quarter of 2010, before principal is impaired.
The foreclosure rate for ACE’s CMBS portfolio at the end of the fourth quarter of 2010, was approximately 2.6 percent.
Below-investment grade corporate fixed income portfolio Below-investment grade securities have different characteristics than investment grade corporate debt securities.
Risk of loss from default by the borrower is greater with below-investment grade securities.
Below-investment grade securities are generally unsecured and are often subordinated to other creditors of the issuer.
Also, issuers of below-investment grade securities usually have higher levels of debt and are more sensitive to adverse economic conditions, such as recession or increasing interest rates, than are investment grade issuers.
At December 31, 2010, our fixed income investment portfolio included belowinvestment grade and non-rated securities which, in total, comprised approximately 14 percent of our fixed income portfolio.
Our below-investment grade and non-rated portfolio includes approximately 650 issuers, with the greatest single exposure being $72 million.
We manage high yield bonds as a distinct and separate asset class from investment grade bonds.
The allocation to high yield bonds is explicitly set by internal management and is targeted to securities in the upper tier of credit quality (BB/B).
Our minimum rating for initial purchase is BB/B.
Six external investment managers are responsible for high yield security selection and portfolio construction.
Our high yield managers have a conservative approach to credit selection and very low historical default experience.
Holdings are highly diversified across industries and subject to a 1.5 percent issuer limit as a percentage of high yield allocation.
We monitor position limits daily through an internal compliance system.
Derivative and structured securities (e. g.  credit default swaps and collateralized mortgage obligations) are not permitted in the high-yield portfolio.
NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS – (continued) ACE LIMITED AND SUBSIDIARIES During 2010, ACE conducted its annual internal, ground-up review of its consolidated A&E liabilities as at December 31, 2009.
As a result of the internal review, the Company increased its net loss reserves for the Brandywine operations, including A&E, by $84 million (net of reinsurance provided by NICO), while the gross loss reserves increased by $247 million.
In addition, the Company increased gross loss reserves for Westchester Specialty’s A&E and other liabilities by $23 million, while the net loss reserves increased by $5 million.
An internal review was also conducted during 2009 of consolidated A&E liabilities as at December 31, 2008.
As a result of that internal review, the Company increased net loss reserves for the Brandywine operations, including A&E, by $44 million (net of reinsurance provided by NICO), while the gross loss reserves increased by $198 million.
This review also resulted in the Company decreasing gross loss reserves for Westchester Specialty’s A&E and other liabilities by $64 million, while the net loss reserves did not change.
In 2010, in addition to ACE’s annual internal review, a team of external actuaries performed an evaluation as to the adequacy of the reserves of Century.
This external review was conducted in accordance with the Brandywine Restructuring Order, which requires that an independent actuarial review of Century’s reserves be completed every two years.
Management takes full responsibility for the estimation of its A&E liabilities.
The difference between the conclusions of the internal and external reviews is an immaterial amount on a net basis after giving effect to the reserve increases for the Brandywine operations described above.
ACE’s A&E reserves are not discounted for GAAP reporting and do not reflect any anticipated future changes in the legal, social, or economic environment, or any benefit from future legislative reforms.
The table below presents a roll forward of ACE’s consolidated A&E loss reserves (excluding other run-off liabilities), allocated loss expense reserves for A&E exposures, and the provision for uncollectible paid and unpaid reinsurance recoverables for the year ended December 31, 2010.
## Table 1 ##
(1) Unallocated loss expense reserves have been removed from December 31, 2009 balances, resulting in reductions to asbestos gross and net reserves of $64 million and $52 million, respectively, and Environmental gross and net reserves of $6 million and $5 million, respectively.
Prior disclosures have included an estimated allocation of reserves for unallocated loss expenses.
The A&E net loss reserves including allocated loss expense reserves and provision for uncollectible reinsurance at December 31, 2010, of $1.276 billion shown in the table above are comprised of $957 million in reserves in respect of Brandywine operations, $122 million of reserves held by Westchester Specialty, $101 million of reserves held by ACE Bermuda and $96 million of reserves held by Insurance – Overseas General.
The incurred activity of $107 million is the result of adverse activity in Brandywine and Westchester of $94 million and $26 million, respectively, offset by favorable activity in Insurance – Overseas General of $13 million on the provision for uncollectible reinsurance.
A portion of the Brandywine incurred activity reflects the allocation of reserve balances for assumed reinsurance and bad debt between A&E and other reserves.
The net figures in the above table reflect third-party reinsurance other than reinsurance provided by NICO under two aggregate excess of loss contracts described below (collectively, the NICO contracts).
ACE excludes the NICO contracts as they cover non-A&E liabilities as well as A&E liabilities.
The split of coverage provided under the NICO contracts for A&E liabilities as compared to non-A&E liabilities is entirely dependent on the timing of the payment of the related claims.
ACE’s ability to make an estimate of this split is not practicable.
ACE believes, instead, that the A&E discussion is best provided excluding the NICO contracts, while separately discussing the NICO contracts in relation to the total subject business, both A&E and non-A&E, covered by those contracts.
With certain exceptions, the NICO contracts provide coverage for the net A&E incurred losses and allocated loss expenses within the limits of coverage and above ACE’s retention levels.
These exceptions include losses arising from certain operations of Insurance – Overseas General and participation by ACE Bermuda as a co-reinsurer or retrocessionaire in the NICO contracts.
The following table segregates loss reserves at December 31, 2010 and 2009, by three broad line of business groupings: property and all other, casualty, and personal accident (A&H).
In the table, loss expenses are defined to include unallocated and allocated loss adjustment expenses.
For certain lines, in particular ACE International and ACE Bermuda products, loss adjustment expenses are partially included in IBNR and partially included in loss expenses.
## Table 2 ##
The judgments used to estimate unpaid loss and loss expense reserves require different considerations depending upon the individual circumstances underlying the insured loss.
For example, the reserves established for high excess casualty claims, A&E claims, claims from major catastrophic events, or the IBNR for our various product lines each require different assumptions and judgments to be made.
Necessary judgments are based on numerous factors and may be revised as additional experience and other data become available and are reviewed, as new or improved methods are developed, or as laws change.
Hence, ultimate loss payments may differ from the estimate of the ultimate liabilities made at the balance sheet date.
Changes to our previous estimates of prior period loss reserves impact the reported calendar year underwriting results by worsening our reported results if the prior year reserves prove to be deficient, or improving our reported results if the prior year reserves prove to be redundant.
The potential for variation in loss reserves is impacted by numerous factors, which we discuss below.
We establish loss and loss expense reserves for our liabilities from claims for all of the insurance and reinsurance business that we write.
For those claims reported by insureds or ceding companies to us prior to the balance sheet date, and where we have sufficient information, our claims personnel establish case reserves as appropriate based on the circumstances of the claim(s), standard claim handling practices, and professional judgment.
In respect of those claims that have been incurred but not reported prior to the balance sheet date, there is, by definition, limited actual information to form the case reserve estimate and reliance is placed upon historical loss experience and actuarial methods to project the ultimate loss obligations and the corresponding amount of IBNR.
Furthermore, for our assumed reinsurance operation, Global Reinsurance, an additional case reserve may be established above the amount notified by the ceding company if the notified case reserve is judged to be insufficient by Global Reinsurance’s claims department (refer to “Assumed reinsurance” below).
We have actuarial staff within each of our operating segments who analyze loss reserves and regularly project estimates of ultimate losses and the required IBNR reserve.
IBNR reserve estimates are generally calculated by first projecting the ultimate amount of expected claims for a product line and subtracting paid losses and case reserves for reported claims.
The judgments involved in projecting the ultimate losses may include the use and interpretation of various standard actuarial reserving
years.
The Company does not yet have a robust set of annuitization experience because most of its clients’ policyholders are not yet eligible to annuitize utilizing the GMIB.
However, for certain clients there are several years of annuitization experience – for those clients the annuitization function reflects the actual experience and has a maximum annuitization rate per annum of 8 percent (a higher maximum applies in the first year a policy is eligible to annuitize utilizing the GMIB – it is over 13 percent).
For most clients there is no currently observable relevant annuitization behavior data and so we use a weighted average (with a heavier weighting on the observed experience noted previously) of three different annuitization functions with maximum annuitization rates per annum of 8 percent, 12 percent, and 30 percent, respectively (with significantly higher rates in the first year a policy is eligible to annuitize utilizing the GMIB).
As noted elsewhere, our GMIB reinsurance treaties include claim limits to protect ACE in the event that actual annuitization behavior is significantly higher than expected.
During 2010, the Company made various changes to assumptions (primarily annuitization and lapse) and methods used to calculate the fair value.
The changes had a net effect of reducing fair value of the liability by $98 million (where the dollar impact of each change was measured in the quarter in which the change was implemented).
During 2010, we recorded realized losses of $64 million primarily due to increasing net fair value of reported GLB reinsurance liabilities resulting substantially from the impact of falling interest rates.
This excludes realized losses of $150 million during 2010 on derivative hedge instruments held to partially offset the risk in the VA guarantee reinsurance portfolio.
These derivatives do not receive hedge accounting treatment.
Refer to “Net Realized Gains (Losses)” for a breakdown of the realized gains on GLB reinsurance and the realized losses on the derivatives for 2010 and 2009.
ACE Tempest Life Re employs a strategy to manage the financial market and policyholder behavior risks embedded in the reinsurance of VA guarantees.
Risk management begins with underwriting a prospective client and guarantee design, with particular focus on protecting ACE’s position from policyholder options that, because of anti-selective behavior, could adversely impact our obligation.
A second layer of risk management is the structure of the reinsurance contracts.
All VA guarantee reinsurance contracts include some form of annual or aggregate claim limit(s).
The exact limits vary by contract, but some examples of typical contract provisions include: ?
annual claim limits, as a percentage of reinsured account or guaranteed value, for GMDBs and GMIBs; ?
annual annuitization rate limits, as a percentage of annuitization eligible account or guaranteed value, for GMIBs; and ?
per policy claim limits, as a percentage of guaranteed value, for GMABs.
A third layer of risk management is the hedging strategy which is focused on mitigating long-term economic losses at a portfolio level.
ACE Tempest Life Re owned financial market instruments as part of the hedging strategy with a fair value of $21 million and $47 million at December 31, 2010, and 2009, respectively.
The instruments are substantially collateralized by our counterparties, on a daily basis.
We also limit the aggregate amount of variable annuity reinsurance guarantee risk we are willing to assume.
The last substantive U. S.  transaction was quoted in mid-2007 and the last transaction in Japan was quoted in late 2007.
The aggregate number of policyholders is currently decreasing through policyholder withdrawals and deaths at a rate of 5-10 percent annually.
Note that GLB claims cannot occur for any reinsured policy until it has reached the end of its “waiting period”.
The vast majority of policies we reinsure reach the end of their “waiting periods” in 2013 or later, as shown in the table below.

Tables referenced above, in order (Table 0 first):
<table><tr><td></td><td colspan="6">S&P Credit Rating</td></tr><tr><td></td><td>AAA</td><td>AA</td><td>A</td><td>BBB</td><td>BB and below</td><td>Total</td></tr><tr><td> Mortgage-backed securities</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Residential mortgage-backed (RMBS)</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Agency RMBS</td><td>$9,564</td><td>$–</td><td>$–</td><td>$–</td><td>$–</td><td>$9,564</td></tr><tr><td>Non-agency RMBS</td><td>351</td><td>23</td><td>23</td><td>55</td><td>947</td><td>1,399</td></tr><tr><td>Total RMBS</td><td>9,915</td><td>23</td><td>23</td><td>55</td><td>947</td><td>10,963</td></tr><tr><td>Commercial mortgage-backed</td><td>1,320</td><td>20</td><td>13</td><td>3</td><td>–</td><td>1,356</td></tr><tr><td> Total mortgage-backed securities</td><td>$11,235</td><td>$43</td><td>$36</td><td>$58</td><td>$947</td><td>$12,319</td></tr></table>
<table><tr><td></td><td colspan="2">Asbestos</td><td colspan="2">Environmental</td><td colspan="2">Total</td></tr><tr><td>(in millions of U.S. dollars)</td><td>Gross</td><td>Net</td><td>Gross</td><td>Net</td><td>Gross</td><td>Net</td></tr><tr><td>Balance at December 31, 2009<sup>-1</sup></td><td>$2,229</td><td>$1,123</td><td>$246</td><td>$234</td><td>$2,475</td><td>$1,357</td></tr><tr><td>Incurred activity</td><td>223</td><td>103</td><td>34</td><td>4</td><td>257</td><td>107</td></tr><tr><td>Payment activity</td><td>-323</td><td>-147</td><td>-74</td><td>-40</td><td>-397</td><td>-187</td></tr><tr><td>Foreign currency revaluation</td><td>1</td><td>-1</td><td>-1</td><td>–</td><td>–</td><td>-1</td></tr><tr><td>Balance at December 31, 2010</td><td>$2,130</td><td>$1,078</td><td>$205</td><td>$198</td><td>$2,335</td><td>$1,276</td></tr></table>
<table><tr><td></td><td colspan="3"> 2010</td><td colspan="3">2009</td></tr><tr><td>(in millions of U.S. dollars)</td><td> Gross</td><td> Ceded</td><td> Net</td><td>Gross</td><td>Ceded</td><td>Net</td></tr><tr><td><i>Property and all other</i></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Case reserves</td><td>$2,871</td><td>$1,325</td><td>$1,546</td><td>$3,149</td><td>$1,600</td><td>$1,549</td></tr><tr><td>Loss expenses</td><td>234</td><td>62</td><td>172</td><td>260</td><td>81</td><td>179</td></tr><tr><td>IBNR reserves</td><td>2,053</td><td>814</td><td>1,239</td><td>2,028</td><td>815</td><td>1,213</td></tr><tr><td>Subtotal</td><td>5,158</td><td>2,201</td><td>2,957</td><td>5,437</td><td>2,496</td><td>2,941</td></tr><tr><td><i>Casualty</i></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Case reserves</td><td>9,203</td><td>2,700</td><td>6,503</td><td>9,506</td><td>3,177</td><td>6,329</td></tr><tr><td>Loss expenses</td><td>4,034</td><td>1,733</td><td>2,301</td><td>3,773</td><td>1,661</td><td>2,112</td></tr><tr><td>IBNR reserves</td><td>17,704</td><td>5,132</td><td>12,572</td><td>17,777</td><td>5,110</td><td>12,667</td></tr><tr><td>Subtotal</td><td>30,941</td><td>9,565</td><td>21,376</td><td>31,056</td><td>9,948</td><td>21,108</td></tr><tr><td><i>A&H</i></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Case reserves</td><td>530</td><td>131</td><td>399</td><td>588</td><td>144</td><td>444</td></tr><tr><td>Loss expenses</td><td>27</td><td>–</td><td>27</td><td>31</td><td>1</td><td>30</td></tr><tr><td>IBNR reserves</td><td>735</td><td>252</td><td>483</td><td>671</td><td>156</td><td>515</td></tr><tr><td>Subtotal</td><td>1,292</td><td>383</td><td>909</td><td>1,290</td><td>301</td><td>989</td></tr><tr><td><i>Total</i></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Case reserves</td><td>12,604</td><td>4,156</td><td>8,448</td><td>13,243</td><td>4,921</td><td>8,322</td></tr><tr><td>Loss expenses</td><td>4,295</td><td>1,795</td><td>2,500</td><td>4,064</td><td>1,743</td><td>2,321</td></tr><tr><td>IBNR reserves</td><td>20,492</td><td>6,198</td><td>14,294</td><td>20,476</td><td>6,081</td><td>14,395</td></tr><tr><td>Total</td><td>$37,391</td><td>$12,149</td><td>$25,242</td><td>$37,783</td><td>$12,745</td><td>$25,038</td></tr></table>

Question: What is the difference between the greatest net of reserves for property in 2009 and 2010？ (in million)
Answer: -3
Reasoning program: subtract(1546,1549)