2.2.0.25falsefalse01120 - Disclosure - Long-Term Compensationtruefalsefalse1falsefalseUSDfalsefalse1/1/2010 - 12/31/2010 USD ($) USD ($) / shares $FROM_Jan01_2010_TO_Dec31_2010http://www.sec.gov/CIK0000899881duration2010-01-01T00:00:002010-12-31T00:00:00USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170EPSDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0SharesStandardhttp://www.xbrl.org/2003/instancesharesxbrli0USDUSD$2true0pld_LongTermCompensationAbstractpldfalsenadurationLong-Term Compensation [Abstract]falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringLong-Term Compensation [Abstract]falsefalseLong-Term Compensation [Abstract]3false0us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlockus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1falsefalsefalse0012. Long-Term Compensation The 2006 long-term incentive plan together with our 1997 long-term incentive plan and outside trustees plan (the “Incentive Plan”) have been approved by our shareholders and provide for grants of share options, stock appreciation rights (“SARs”), full value awards and cash incentive awards to employees and other persons providing services to us and our subsidiaries, including outside trustees. Approximately 41.2 million common shares in the aggregate were authorized under the Incentive Plan, of which 17.3 million common shares were available for future issuance at December 31, 2010. In any one calendar-year period, no participant shall be granted: (i) more than 500,000 share options and SARs; (ii) more than 500,000 full value performance based awards; or (iii) more than $10,000,000 in cash incentive awards. Common shares may be awarded under the Incentive Plan until it is terminated by the Board.  Share Options We have granted various share options to our employees and outside trustees, subject to certain conditions. Each share option is exercisable into one common share. The holders of share options granted before June 2001 earn DEUs on December 31st of each year until the earlier of the date the underlying share option is exercised or the expiration date of the underlying share option. At December 31, 2010, there were 10,000 share options with a weighted average exercise price of $20.80 that will earn DEUs until their expiration in May 2011. Share options granted to employees generally have graded vesting over a four-year period and have an exercise price equal to the market price on the date of grant. Share options granted to outside trustees generally vest immediately. There were no share options granted in 2010 or 2009. Share options outstanding at December 31, 2010, were as follows: <div><table style="border-collapse:collapse;margin-top:20px;"><tr style="height: 42px"><td style="width: 12px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 12px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 12px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 234px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:234px;"> </td><td style="width: 82px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:82px;">Number of Options</td><td style="width: 8px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:8px;"> </td><td style="width: 82px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:82px;">Exercise Price</td><td style="width: 8px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:8px;"> </td><td style="width: 82px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:82px;">Expiration Date</td><td style="width: 8px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:8px;"> </td><td style="width: 85px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:85px;">Weighted Average Remaining Life (in years)</td></tr><tr style="height: 12px"><td colspan="4" style="width: 270px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:270px;">Outside trustees</td><td style="width: 82px; border-top-style:solid;border-top-width:1px;text-align:right;border-color:#000000;min-width:82px;">70,000</td><td style="width: 8px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 82px; border-top-style:solid;border-top-width:1px;text-align:right;border-color:#000000;min-width:82px;">$20.80 - $43.80</td><td style="width: 8px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 82px; border-top-style:solid;border-top-width:1px;text-align:center;border-color:#000000;min-width:82px;">2011 - 2015</td><td style="width: 8px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 85px; border-top-style:solid;border-top-width:1px;text-align:right;border-color:#000000;min-width:85px;">2.8</td></tr><tr style="height: 12px"><td colspan="4" style="width: 270px; text-align:left;border-color:#000000;min-width:270px;">Incentive Plan:</td><td style="width: 82px; text-align:right;border-color:#000000;min-width:82px;"> </td><td style="width: 8px; text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 82px; text-align:left;border-color:#000000;min-width:82px;"> </td><td style="width: 8px; text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 82px; text-align:left;border-color:#000000;min-width:82px;"> </td><td style="width: 8px; text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 85px; text-align:right;border-color:#000000;min-width:85px;"> </td></tr><tr style="height: 12px"><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td colspan="3" style="width: 258px; text-align:left;border-color:#000000;min-width:258px;">2001 grants</td><td style="width: 82px; text-align:right;border-color:#000000;min-width:82px;"> 190,548</td><td style="width: 8px; text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 82px; text-align:right;border-color:#000000;min-width:82px;">$20.68 - $22.02</td><td style="width: 8px; text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 82px; text-align:center;border-color:#000000;min-width:82px;">2011</td><td style="width: 8px; text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 85px; text-align:right;border-color:#000000;min-width:85px;">0.7</td></tr><tr style="height: 12px"><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td colspan="3" style="width: 258px; text-align:left;border-color:#000000;min-width:258px;">2002 grants</td><td style="width: 82px; text-align:right;border-color:#000000;min-width:82px;"> 376,000</td><td style="width: 8px; text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 82px; text-align:right;border-color:#000000;min-width:82px;">$22.98 - $24.76</td><td style="width: 8px; text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 82px; text-align:center;border-color:#000000;min-width:82px;">2012</td><td style="width: 8px; text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 85px; text-align:right;border-color:#000000;min-width:85px;">1.7</td></tr><tr style="height: 12px"><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td colspan="3" style="width: 258px; text-align:left;border-color:#000000;min-width:258px;">2003 grants</td><td style="width: 82px; text-align:right;border-color:#000000;min-width:82px;"> 396,599</td><td style="width: 8px; text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 82px; text-align:right;border-color:#000000;min-width:82px;">$30.00 - $31.27</td><td style="width: 8px; text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 82px; text-align:center;border-color:#000000;min-width:82px;">2013</td><td style="width: 8px; text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 85px; text-align:right;border-color:#000000;min-width:85px;">2.5</td></tr><tr style="height: 12px"><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td colspan="3" style="width: 258px; text-align:left;border-color:#000000;min-width:258px;">2004 grants</td><td style="width: 82px; text-align:right;border-color:#000000;min-width:82px;"> 717,750</td><td style="width: 8px; text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 82px; text-align:right;border-color:#000000;min-width:82px;">$34.93</td><td style="width: 8px; text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 82px; text-align:center;border-color:#000000;min-width:82px;">2014</td><td style="width: 8px; text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 85px; text-align:right;border-color:#000000;min-width:85px;">3.7</td></tr><tr style="height: 12px"><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td colspan="3" style="width: 258px; text-align:left;border-color:#000000;min-width:258px;">2005 grants</td><td style="width: 82px; text-align:right;border-color:#000000;min-width:82px;"> 325,948</td><td style="width: 8px; text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 82px; text-align:right;border-color:#000000;min-width:82px;">$45.29 - $45.46</td><td style="width: 8px; text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 82px; text-align:center;border-color:#000000;min-width:82px;">2015</td><td style="width: 8px; text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 85px; text-align:right;border-color:#000000;min-width:85px;">4.9</td></tr><tr style="height: 12px"><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td colspan="3" style="width: 258px; text-align:left;border-color:#000000;min-width:258px;">2006 grants</td><td style="width: 82px; text-align:right;border-color:#000000;min-width:82px;"> 186,458</td><td style="width: 8px; text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 82px; text-align:right;border-color:#000000;min-width:82px;">$54.51 - $59.92</td><td style="width: 8px; text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 82px; text-align:center;border-color:#000000;min-width:82px;">2016</td><td style="width: 8px; text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 85px; text-align:right;border-color:#000000;min-width:85px;">6.0</td></tr><tr style="height: 12px"><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td colspan="3" style="width: 258px; text-align:left;border-color:#000000;min-width:258px;">2007 grants</td><td style="width: 82px; text-align:right;border-color:#000000;min-width:82px;"> 209,205</td><td style="width: 8px; text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 82px; text-align:right;border-color:#000000;min-width:82px;">$60.60</td><td style="width: 8px; text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 82px; text-align:center;border-color:#000000;min-width:82px;">2017</td><td style="width: 8px; text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 85px; text-align:right;border-color:#000000;min-width:85px;">7.0</td></tr><tr style="height: 12px"><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td colspan="3" style="width: 258px; text-align:left;border-color:#000000;min-width:258px;">2008 grants</td><td style="width: 82px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:82px;"> 750,000</td><td style="width: 8px; text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 82px; text-align:right;border-color:#000000;min-width:82px;">$6.87</td><td style="width: 8px; text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 82px; text-align:center;border-color:#000000;min-width:82px;">2018</td><td style="width: 8px; text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 85px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:85px;">7.9</td></tr><tr style="height: 12px"><td style="width: 12px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 12px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:12px;"> </td><td colspan="2" style="width: 246px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:246px;">Total</td><td style="width: 82px; border-top-style:solid;border-top-width:1px;border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:82px;"> 3,222,508</td><td style="width: 8px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 82px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:82px;"> </td><td style="width: 8px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 82px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:82px;"> </td><td style="width: 8px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 85px; border-top-style:solid;border-top-width:1px;border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:85px;">4.6</td></tr></table></div>The activity for the year ended December 31, 2010, with respect to our share options is presented below: <div><table style="border-collapse:collapse;margin-top:20px;"><tr style="height: 13px"><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 210px; text-align:left;border-color:#000000;min-width:210px;"> </td><td colspan="4" style="width: 146px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:146px;">Options Outstanding</td><td style="width: 8px; text-align:center;border-color:#000000;min-width:8px;"> </td><td colspan="6" style="width: 249px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:249px;">Options Exercisable</td></tr><tr style="height: 43px"><td style="width: 12px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 210px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:210px;"> </td><td style="width: 65px; border-top-style:solid;border-top-width:1px;border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:65px;">Number of Options</td><td style="width: 8px; border-top-style:solid;border-top-width:1px;border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:8px;"> </td><td colspan="2" style="width: 73px; border-top-style:solid;border-top-width:1px;border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:73px;">Weighted Average Exercise Price</td><td style="width: 8px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 65px; border-top-style:solid;border-top-width:1px;border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:65px;">Number of Options</td><td style="width: 8px; border-top-style:solid;border-top-width:1px;border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:8px;"> </td><td style="width: 8px; border-top-style:solid;border-top-width:1px;border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:8px;"> </td><td style="width: 80px; border-top-style:solid;border-top-width:1px;border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:80px;">Weighted Average Exercise Price</td><td style="width: 8px; border-top-style:solid;border-top-width:1px;border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:8px;"> </td><td style="width: 80px; border-top-style:solid;border-top-width:1px;border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:80px;">Weighted Average Life (in years)</td></tr><tr style="height: 15px"><td colspan="2" style="width: 222px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:222px;">Balance at January 1, 2010</td><td style="width: 65px; border-top-style:solid;border-top-width:1px;text-align:right;border-color:#000000;min-width:65px;"> 6,038,700</td><td style="width: 8px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 8px; border-top-style:solid;border-top-width:1px;text-align:center;border-color:#000000;min-width:8px;">$</td><td style="width: 65px; border-top-style:solid;border-top-width:1px;text-align:right;border-color:#000000;min-width:65px;"> 32.25</td><td style="width: 8px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 65px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:65px;"> </td><td style="width: 8px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 8px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 80px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:80px;"> </td><td style="width: 8px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 80px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:80px;"> </td></tr><tr style="height: 15px"><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 210px; text-align:left;border-color:#000000;min-width:210px;">Exercised</td><td style="width: 65px; text-align:right;border-color:#000000;min-width:65px;"> (387,500)</td><td style="width: 8px; text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 8px; text-align:center;border-color:#000000;min-width:8px;"> </td><td style="width: 65px; text-align:right;border-color:#000000;min-width:65px;"> 6.87</td><td style="width: 8px; text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 65px; text-align:left;border-color:#000000;min-width:65px;"> </td><td style="width: 8px; text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 8px; text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 80px; text-align:left;border-color:#000000;min-width:80px;"> </td><td style="width: 8px; text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 80px; text-align:left;border-color:#000000;min-width:80px;"> </td></tr><tr style="height: 15px"><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 210px; text-align:left;border-color:#000000;min-width:210px;">Surrendered and cancelled</td><td style="width: 65px; text-align:right;border-color:#000000;min-width:65px;"> (1,842,997)</td><td style="width: 8px; text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 8px; text-align:center;border-color:#000000;min-width:8px;"> </td><td style="width: 65px; text-align:right;border-color:#000000;min-width:65px;"> 43.30</td><td style="width: 8px; text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 65px; text-align:left;border-color:#000000;min-width:65px;"> </td><td style="width: 8px; text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 8px; text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 80px; text-align:left;border-color:#000000;min-width:80px;"> </td><td style="width: 8px; text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 80px; text-align:left;border-color:#000000;min-width:80px;"> </td></tr><tr style="height: 15px"><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 210px; text-align:left;border-color:#000000;min-width:210px;">Forfeited</td><td style="width: 65px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:65px;"> (585,695)</td><td style="width: 8px; text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 8px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:8px;"> </td><td style="width: 65px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:65px;"> 27.43</td><td style="width: 8px; text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 65px; text-align:left;border-color:#000000;min-width:65px;"> </td><td style="width: 8px; text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 8px; text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 80px; text-align:left;border-color:#000000;min-width:80px;"> </td><td style="width: 8px; text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 80px; text-align:left;border-color:#000000;min-width:80px;"> </td></tr><tr style="height: 15px"><td colspan="2" style="width: 222px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:222px;">Balance at December 31, 2010</td><td style="width: 65px; border-top-style:solid;border-top-width:1px;border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:65px;"> 3,222,508</td><td style="width: 8px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 8px; border-top-style:solid;border-top-width:1px;border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:8px;">$</td><td style="width: 65px; border-top-style:solid;border-top-width:1px;border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:65px;"> 29.86</td><td style="width: 8px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 65px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:65px;"> 2,614,424</td><td style="width: 8px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 8px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:8px;">$</td><td style="width: 80px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:80px;">34.27</td><td style="width: 8px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 80px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:80px;">3.7</td></tr></table></div>On July 9, 2010, we completed a one-time share option exchange program, which was approved by our shareholders at our annual meeting, to allow certain of our employees to surrender for cancellation outstanding share options with an exercise price that was greater than $15.04 per share in exchange for a lesser number of RSUs based on the fair value of the option and the RSU at the time of the exchange. The unamortized cost of the share options surrendered and cancelled was included as a component of the value of the RSUs granted. The total value of the RSUs, equal to the unamortized compensation expense associated with the related eligible unvested options surrendered, will be recognized as compensation expense over the applicable vesting period of the new RSUs. As the fair value of each RSU granted approximated the fair value of the eligible options surrendered in exchange for the RSUs, each measured on July 9, 2010, there was no incremental compensation cost. As a result of the program, 1,842,997 options were surrendered and cancelled and 522,328 RSUs were granted. The activity for the year ended December 31, 2010, with respect to our non-vested share options is presented below: <div><table style="border-collapse:collapse;margin-top:20px;"><tr style="height: 15px"><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 363px; text-align:left;border-color:#000000;min-width:363px;"> </td><td style="width: 99px; text-align:center;border-color:#000000;min-width:99px;">Number of</td><td style="width: 8px; text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 8px; text-align:center;border-color:#000000;min-width:8px;"> </td><td style="width: 111px; text-align:center;border-color:#000000;min-width:111px;">Weighted Average</td></tr><tr style="height: 15px"><td style="width: 12px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 12px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 12px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 363px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:363px;"> </td><td style="width: 99px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:99px;">Options</td><td style="width: 8px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:8px;"> </td><td style="width: 8px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:8px;"> </td><td style="width: 111px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:111px;">Grant-Date Fair Value</td></tr><tr style="height: 12px"><td colspan="4" style="width: 399px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:399px;">Balance at January 1, 2010</td><td style="width: 99px; border-top-style:solid;border-top-width:1px;text-align:right;border-color:#000000;min-width:99px;">1,297,952</td><td style="width: 8px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 8px; border-top-style:solid;border-top-width:1px;text-align:center;border-color:#000000;min-width:8px;">$</td><td style="width: 111px; border-top-style:solid;border-top-width:1px;text-align:right;border-color:#000000;min-width:111px;">5.01</td></tr><tr style="height: 12px"><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td colspan="3" style="width: 387px; text-align:left;border-color:#000000;min-width:387px;">Vested</td><td style="width: 99px; text-align:right;border-color:#000000;min-width:99px;">(383,852)</td><td style="width: 8px; text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 8px; text-align:center;border-color:#000000;min-width:8px;"> </td><td style="width: 111px; text-align:right;border-color:#000000;min-width:111px;">3.92</td></tr><tr style="height: 12px"><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td colspan="3" style="width: 387px; text-align:left;border-color:#000000;min-width:387px;">Surrendered and cancelled</td><td style="width: 99px; text-align:right;border-color:#000000;min-width:99px;">(244,541)</td><td style="width: 8px; text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 8px; text-align:center;border-color:#000000;min-width:8px;"> </td><td style="width: 111px; text-align:right;border-color:#000000;min-width:111px;">11.13</td></tr><tr style="height: 12px"><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td colspan="3" style="width: 387px; text-align:left;border-color:#000000;min-width:387px;">Forfeited</td><td style="width: 99px; text-align:right;border-color:#000000;min-width:99px;">(61,475)</td><td style="width: 8px; text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 8px; text-align:center;border-color:#000000;min-width:8px;"> </td><td style="width: 111px; text-align:right;border-color:#000000;min-width:111px;">6.96</td></tr><tr style="height: 12px"><td colspan="4" style="width: 399px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:399px;">Balance at December 31, 2010</td><td style="width: 99px; border-top-style:solid;border-top-width:1px;border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:99px;">608,084</td><td style="width: 8px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:8px;"> </td><td style="width: 8px; border-top-style:solid;border-top-width:1px;border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:8px;">$</td><td style="width: 111px; border-top-style:solid;border-top-width:1px;border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:111px;">3.04</td></tr></table></div>Full Value Awards We grant full value awards, generally in the form of restricted share units (“RSUs”) and performance-based awards, to certain employees, generally on an annual basis. These share awards, each representing one common share, generally vest ratably over a continued service period, do not carry voting rights and earn dividends or DEUs (at our common share dividend rate) over the vesting period. The fair values of the awards are charged to compensation expense. Cash dividends and DEUs are charged to retained earnings and factored into the computation of the fair value of the underlying share award at grant date.  Restricted Share Units RSUs are valued on the grant date based on the market price of a common share on that date. The vesting period for RSUs has generally been three to four years. RSUs granted in 2010 and 2009 primarily have a vesting period of three years. We recognize the value of the RSUs earned as compensation expense over the applicable vesting period. Through 2009, RSUs earned DEUs that vested according to the underlying RSU. In 2010, we began to pay cash dividends on the RSUs during the vesting period. We issue fully vested deferred share awards to our outside trustees, which earn DEUs that are also fully vested. The fair value of the deferred share awards, which is the market price of a common share on the grant date, is expensed at the time of grant. The weighted average fair value of RSUs and deferred share awards granted during the years 2010, 2009 and 2008 was $12.31, $6.52 and $10.51, respectively. Performance-Based Shares We granted performance-based shares in the form of performance share awards (“PSAs”) in 2010 and 2009 and contingent performance shares (“CPSs”) from 2005 to 2008. Employees are granted a targeted number of either PSAs or CPSs, which are then earned based on specified performance criteria over a performance period. Earned PSAs are also subject to an additional vesting period. During the performance period, the unearned PSAs and CPSs accrue dividends, which will be earned and vested according to the underlying award. Through 2009, earned PSAs subject to an additional vesting period also earned DEUs, which vested according to the underlying award. In 2010, we began to pay cash dividends on earned PSAs during the additional vesting period.  In 2010 and 2009, PSAs were granted to certain employees at a targeted amount that could be earned based on specific individual and company performance criteria, generally over a one-year performance period. Employees could earn between 0% and 200% of PSAs granted in 2010 (with a performance period ending December 31, 2010) and between 50% and 150% of PSAs granted in 2009 (with a performance period ending December 31, 2009). The PSAs vest ratably over a three-year period from the date of grant. In 2010, we granted 543,025 PSAs and based on the attainment of specified individual and company performance goals, a total of 506,145 were earned. In 2009, we granted 829,571 PSAs and based on the attainment of specified individual and company performance goals, a total of 1,019,884 were earned. PSAs are valued based upon the market price of a common share on the date of grant. We recognize the value of the PSAs earned as compensation expense over the vesting period, which includes the performance period.  CPSs were granted to certain employees each year from 2005 to 2007. The CPSs could be earned based on our ranking in a defined subset of companies in the National Association of Real Estate Investment Trust's (“NAREIT's”) published index. The amount of CPSs earned was based on our ranking at the end of the respective performance period, generally three years, and could have ranged from 0% to 200% of the targeted award. In calculating compensation expense, we considered the CPSs to have a market condition and, therefore, we estimated the grant date fair value of the CPSs using a pricing valuation model. The value of the CPSs (grant date fair value of the targeted CPSs granted) was recognized as compensation expense over the performance period. The compensation expense recognized is not adjusted to reflect the actual CPSs earned at the end of the performance period, but is adjusted for forfeited awards. At December 31, 2010, there were 105,985 CPSs outstanding. The performance period applicable to the outstanding CPSs ended on December 31, 2010 and in January 2011, all of these CPSs were cancelled based on the results from the performance period.  The weighted-average fair value of the PSAs and CPSs granted during the years 2010, 2009 and 2008 was $13.68, $6.93 and $22.72, respectively.  Summary of Activity of our Full Value Awards Activity with respect to our full value awards is as follows:<div><table style="border-collapse:collapse;margin-top:20px;"><tr style="height: 17px"><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 252px; text-align:left;border-color:#000000;min-width:252px;"> </td><td colspan="4" style="width: 246px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:246px;">Shares Outstanding</td><td style="width: 4px; text-align:center;border-color:#000000;min-width:4px;"> </td><td style="width: 111px; text-align:left;border-color:#000000;min-width:111px;"> </td></tr><tr style="height: 15px"><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 252px; text-align:left;border-color:#000000;min-width:252px;"> </td><td style="width: 99px; border-top-style:solid;border-top-width:1px;text-align:center;border-color:#000000;min-width:99px;">Number of</td><td style="width: 12px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 12px; border-top-style:solid;border-top-width:1px;text-align:center;border-color:#000000;min-width:12px;"> </td><td style="width: 123px; border-top-style:solid;border-top-width:1px;text-align:center;border-color:#000000;min-width:123px;">Weighted Average</td><td style="width: 4px; text-align:center;border-color:#000000;min-width:4px;"> </td><td style="width: 111px; text-align:center;border-color:#000000;min-width:111px;">Number of</td></tr><tr style="height: 15px"><td style="width: 12px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 252px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:252px;"> </td><td style="width: 99px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:99px;">Shares</td><td style="width: 12px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 12px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:12px;"> </td><td style="width: 123px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:123px;">Grant-Date Fair Value</td><td style="width: 4px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:4px;"> </td><td style="width: 111px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:111px;">Shares Vested</td></tr><tr style="height: 15px"><td colspan="2" style="width: 264px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:264px;">Balance at January 1, 2010</td><td style="width: 99px; border-top-style:solid;border-top-width:1px;text-align:right;border-color:#000000;min-width:99px;"> 3,401,784</td><td style="width: 12px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 12px; border-top-style:solid;border-top-width:1px;text-align:center;border-color:#000000;min-width:12px;">$</td><td style="width: 123px; border-top-style:solid;border-top-width:1px;text-align:right;border-color:#000000;min-width:123px;">20.47</td><td style="width: 4px; border-top-style:solid;border-top-width:1px;text-align:right;border-color:#000000;min-width:4px;"> </td><td style="width: 111px; border-top-style:solid;border-top-width:1px;border-bottom-style:double;border-bottom-width:3px;text-align:right;border-color:#000000;min-width:111px;"> 143,268</td></tr><tr style="height: 15px"><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 252px; text-align:left;border-color:#000000;min-width:252px;">Granted</td><td style="width: 99px; text-align:right;border-color:#000000;min-width:99px;"> 2,343,395</td><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 12px; text-align:center;border-color:#000000;min-width:12px;"> </td><td style="width: 123px; text-align:right;border-color:#000000;min-width:123px;">10.60</td><td style="width: 4px; text-align:right;border-color:#000000;min-width:4px;"> </td><td style="width: 111px; border-top-style:double;border-top-width:3px;text-align:left;border-color:#000000;min-width:111px;"> </td></tr><tr style="height: 15px"><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 252px; text-align:left;border-color:#000000;min-width:252px;">Distributed</td><td style="width: 99px; text-align:right;border-color:#000000;min-width:99px;"> (1,390,664)</td><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 12px; text-align:center;border-color:#000000;min-width:12px;"> </td><td style="width: 123px; text-align:right;border-color:#000000;min-width:123px;">21.24</td><td style="width: 4px; text-align:right;border-color:#000000;min-width:4px;"> </td><td style="width: 111px; text-align:left;border-color:#000000;min-width:111px;"> </td></tr><tr style="height: 15px"><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 252px; text-align:left;border-color:#000000;min-width:252px;">Forfeited</td><td style="width: 99px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:99px;"> (169,174)</td><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 12px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:12px;"> </td><td style="width: 123px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:123px;">41.45</td><td style="width: 4px; text-align:right;border-color:#000000;min-width:4px;"> </td><td style="width: 111px; text-align:left;border-color:#000000;min-width:111px;"> </td></tr><tr style="height: 15px"><td colspan="2" style="width: 264px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:264px;">Balance at December 31, 2010</td><td style="width: 99px; border-top-style:solid;border-top-width:1px;border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:99px;"> 4,185,341</td><td style="width: 12px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 12px; border-top-style:solid;border-top-width:1px;border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:12px;">$</td><td style="width: 123px; border-top-style:solid;border-top-width:1px;border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:123px;">13.84</td><td style="width: 4px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:4px;"> </td><td style="width: 111px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:111px;"> 196,988</td></tr></table></div>Total remaining compensation cost related to unvested RSUs, CPSs and PSAs as of December 31, 2010, is $27.3 million, prior to adjustments for capitalized amounts due to our development and leasing activities. The remaining expense will be recognized through 2014, which equates to a weighted average period of 1.5 years. The activity for the year ended December 31, 2010, with respect to our non-vested RSUs, CPSs and PSAs is presented below: <div><table style="border-collapse:collapse;margin-top:20px;"><tr style="height: 15px"><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 383px; text-align:left;border-color:#000000;min-width:383px;"> </td><td style="width: 99px; text-align:center;border-color:#000000;min-width:99px;">Number of</td><td style="width: 8px; text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 12px; text-align:center;border-color:#000000;min-width:12px;"> </td><td style="width: 111px; text-align:center;border-color:#000000;min-width:111px;">Weighted Average</td></tr><tr style="height: 15px"><td style="width: 12px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 383px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:383px;"> </td><td style="width: 99px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:99px;">Shares</td><td style="width: 8px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 12px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 111px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:111px;">Grant-Date Fair Value</td></tr><tr style="height: 15px"><td colspan="2" style="width: 395px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:395px;">Balance at January 1, 2010</td><td style="width: 99px; border-top-style:solid;border-top-width:1px;text-align:right;border-color:#000000;min-width:99px;"> 3,258,516</td><td style="width: 8px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 12px; border-top-style:solid;border-top-width:1px;text-align:center;border-color:#000000;min-width:12px;">$</td><td style="width: 111px; border-top-style:solid;border-top-width:1px;text-align:right;border-color:#000000;min-width:111px;"> 20.26</td></tr><tr style="height: 15px"><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 383px; text-align:left;border-color:#000000;min-width:383px;">Granted</td><td style="width: 99px; text-align:right;border-color:#000000;min-width:99px;"> 2,343,395</td><td style="width: 8px; text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 12px; text-align:center;border-color:#000000;min-width:12px;"> </td><td style="width: 111px; text-align:right;border-color:#000000;min-width:111px;"> 10.60</td></tr><tr style="height: 15px"><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 383px; text-align:left;border-color:#000000;min-width:383px;">Vested</td><td style="width: 99px; text-align:right;border-color:#000000;min-width:99px;"> (1,444,384)</td><td style="width: 8px; text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 12px; text-align:center;border-color:#000000;min-width:12px;"> </td><td style="width: 111px; text-align:right;border-color:#000000;min-width:111px;"> 20.54</td></tr><tr style="height: 15px"><td style="width: 12px; text-align:left;border-color:#000000;min-width:12px;"> </td><td style="width: 383px; text-align:left;border-color:#000000;min-width:383px;">Forfeited</td><td style="width: 99px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:99px;"> (169,174)</td><td style="width: 8px; text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 12px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:12px;"> </td><td style="width: 111px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:111px;"> 41.45</td></tr><tr style="height: 15px"><td colspan="2" style="width: 395px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:395px;">Balance at December 31, 2010</td><td style="width: 99px; border-top-style:solid;border-top-width:1px;border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:99px;"> 3,988,353</td><td style="width: 8px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 12px; border-top-style:solid;border-top-width:1px;border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:12px;">$</td><td style="width: 111px; border-top-style:solid;border-top-width:1px;border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:111px;"> 13.58</td></tr></table></div>Compensation Expense During the years ended December 31, 2010, 2009 and 2008, we recognized $25.1 million, $17.2 million and $28.3 million, respectively, of compensation expense including awards granted to our outside trustees and net of forfeited awards. These amounts include expense reported as General and Administrative Expenses, RIF charges and Discontinued Operations and are net of $5.3 million, $5.8 million and $12.1 million, respectively, that was capitalized due to our development and leasing activities. We calculated the fair value of the share options granted in 2008 (no share options have been granted since 2008) using a Black-Scholes pricing model and the following weighted average assumptions for the years ended December 31: <div><table style="border-collapse:collapse;margin-top:20px;"><tr style="height: 12px"><td style="width: 8px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:8px;"> </td><td style="width: 369px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:369px;"> </td><td style="width: 70px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:70px;"> </td><td style="width: 10px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:10px;"> </td><td style="width: 8px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:8px;"> </td><td style="width: 70px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:70px;"> </td><td style="width: 10px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:70px;">2008</td><td style="width: 10px; border-bottom-style:solid;border-bottom-width:1px;text-align:center;border-color:#000000;min-width:10px;"> </td></tr><tr style="height: 12px"><td colspan="6" style="width: 535px; border-top-style:solid;border-top-width:1px;text-align:left;border-color:#000000;min-width:535px;">Risk-free interest rate</td><td style="width: 10px; border-top-style:solid;border-top-width:1px;text-align:center;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; border-top-style:solid;border-top-width:1px;text-align:right;border-color:#000000;min-width:70px;"> 2.56</td><td style="width: 10px; border-top-style:solid;border-top-width:1px;text-align:center;border-color:#000000;min-width:10px;">%</td></tr><tr style="height: 12px"><td colspan="6" style="width: 535px; text-align:left;border-color:#000000;min-width:535px;">Dividend yield</td><td style="width: 10px; text-align:center;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; text-align:right;border-color:#000000;min-width:70px;"> 1.92</td><td style="width: 10px; text-align:center;border-color:#000000;min-width:10px;">%</td></tr><tr style="height: 12px"><td colspan="6" style="width: 535px; text-align:left;border-color:#000000;min-width:535px;">Volatility</td><td style="width: 10px; text-align:center;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; text-align:right;border-color:#000000;min-width:70px;"> 40.35</td><td style="width: 10px; text-align:center;border-color:#000000;min-width:10px;">%</td></tr><tr style="height: 12px"><td colspan="6" style="width: 535px; border-bottom-style:solid;border-bottom-width:1px;text-align:left;border-color:#000000;min-width:535px;">Weighted average option life</td><td style="width: 10px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:10px;"> </td><td style="width: 70px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:70px;">5.8 years</td><td style="width: 10px; border-bottom-style:solid;border-bottom-width:1px;text-align:right;border-color:#000000;min-width:10px;"> </td></tr></table></div>We use historical data to estimate dividend yield, share option exercises, expected term and employee departure behavior used in the Black-Scholes pricing model. The risk-free interest rate for periods within the expected term of the share option is based on the U.S. Treasury yield curve in effect at the time of grant. To calculate expected volatility, we use historical volatility of our common shares and implied volatility of traded options on our common shares. Other Plans We have a 401(k) Savings Plan and Trust (“401(k) Plan”), that provides for matching employer contributions of 50 cents for every dollar contributed by an employee, up to 6% of the employee's annual compensation (within the statutory compensation limit). Vesting in the matching employer contributions is based on the employee's years of service, with 20% vesting each year of service, over a five-year period. While we have authorized 190,000 ProLogis common shares for issuance under the 401(k) Plan, to date no matching contributions have been made with ProLogis common shares.  We have a nonqualified savings plan to provide benefits for certain employees. The purpose of this plan is to allow highly compensated employees the opportunity to defer the receipt and income taxation of a certain portion of their compensation in excess of the amount permitted under the 401(k) Plan. We match the lesser of (a) 50% of the sum of deferrals under both the 401(k) Plan and this plan, and (b) 3% of total compensation up to certain levels. The matching contributions vest in the same manner as the 401(k) Plan.  On a combined basis for both plans, our contributions under the matching provisions were $1.3 million, $1.1 million and $1.4 million for 2010, 2009 and 2008, respectively12. Long-Term Compensation The 2006 long-term incentive plan together with our 1997 long-term incentive plan and outside trustees plan (thefalsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringDisclosure of compensation-related costs for share-based compensation which may include disclosure of policies, compensation plan details, allocation of stock compensation, incentive distributions, share-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph 64, 65, A240 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Statement of Position (SOP) -Number 93-6 -Paragraph 53 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 14 falsefalseLong-Term Compensation12Long-Term CompensationUnKnownUnKnownUnKnownUnKnownfalsetrue