<?xml version="1.0" encoding="utf-8"?>
<InstanceReport xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Version>1.0.0.3</Version>
  <hasSegments>false</hasSegments>
  <ReportName>SHAREHOLDERS' EQUITY</ReportName>
  <RoundingOption />
  <Columns>
    <Column>
      <LabelColumn>false</LabelColumn>
      <Id>1</Id>
      <Labels>
        <Label Id="1" Label="12 Months Ended" />
        <Label Id="2" Label="Dec. 31, 2009" />
      </Labels>
      <CurrencySymbol>$</CurrencySymbol>
      <hasSegments>false</hasSegments>
      <hasScenarios>false</hasScenarios>
      <Segments />
      <Scenarios />
      <Units />
    </Column>
  </Columns>
  <Rows>
    <Row>
      <Id>2</Id>
      <Label>Notes to Consolidated Financial Statements</Label>
      <Level>0</Level>
      <ElementName>sre_NotesToConsolidatedFinancialStatementsAbstract</ElementName>
      <ElementPrefix>sre</ElementPrefix>
      <IsBaseElement>false</IsBaseElement>
      <BalanceType>na</BalanceType>
      <PeriodType>duration</PeriodType>
      <ElementDataType>string</ElementDataType>
      <ShortDefinition>No definition available.</ShortDefinition>
      <IsReportTitle>false</IsReportTitle>
      <IsSegmentTitle>false</IsSegmentTitle>
      <IsSubReportEnd>false</IsSubReportEnd>
      <IsCalendarTitle>false</IsCalendarTitle>
      <IsTuple>false</IsTuple>
      <IsAbstractGroupTitle>true</IsAbstractGroupTitle>
      <IsBeginningBalance>false</IsBeginningBalance>
      <IsEndingBalance>false</IsEndingBalance>
      <IsEPS>false</IsEPS>
      <Cells>
        <Cell>
          <Id>1</Id>
          <ShowCurrencySymbol>false</ShowCurrencySymbol>
          <IsNumeric>false</IsNumeric>
          <NumericAmount>0</NumericAmount>
          <RoundedNumericAmount>0</RoundedNumericAmount>
          <NonNumbericText />
          <NonNumericTextHeader />
          <FootnoteIndexer />
          <hasSegments>false</hasSegments>
          <hasScenarios>false</hasScenarios>
        </Cell>
      </Cells>
      <ElementDefenition>No definition available.</ElementDefenition>
      <IsTotalLabel>false</IsTotalLabel>
    </Row>
    <Row>
      <Id>3</Id>
      <Label>Shareholders' Equity Disclosure</Label>
      <Level>1</Level>
      <ElementName>us-gaap_StockholdersEquityNoteDisclosureTextBlock</ElementName>
      <ElementPrefix>us-gaap</ElementPrefix>
      <IsBaseElement>true</IsBaseElement>
      <BalanceType>na</BalanceType>
      <PeriodType>duration</PeriodType>
      <ElementDataType>string</ElementDataType>
      <ShortDefinition>No definition available.</ShortDefinition>
      <IsReportTitle>false</IsReportTitle>
      <IsSegmentTitle>false</IsSegmentTitle>
      <IsSubReportEnd>false</IsSubReportEnd>
      <IsCalendarTitle>false</IsCalendarTitle>
      <IsTuple>false</IsTuple>
      <IsAbstractGroupTitle>false</IsAbstractGroupTitle>
      <IsBeginningBalance>false</IsBeginningBalance>
      <IsEndingBalance>false</IsEndingBalance>
      <IsEPS>false</IsEPS>
      <Cells>
        <Cell>
          <Id>1</Id>
          <ShowCurrencySymbol>false</ShowCurrencySymbol>
          <IsNumeric>false</IsNumeric>
          <NumericAmount>0</NumericAmount>
          <RoundedNumericAmount>0</RoundedNumericAmount>
          <NonNumbericText>&lt;div style="font-size:12pt"&gt;&lt;p&gt;We are authorized to issue 750,000,000 shares of no-par-value common stock. In addition, we are authorized to issue 50,000,000 shares of preferred stock having rights, preferences and privileges that would be established by the Sempra Energy board of directors at the time of issuance. &lt;br /&gt;Shares of common stock held by the ESOP were 868,173; 1,177,196 and 1,488,046 at December 31, 2009, 2008 and 2007, respectively. These shares are unallocated and therefore excluded from the computation of EPS.&lt;br /&gt;Excluding shares held by the ESOP, common stock activity consisted of the following:&lt;/p&gt;&lt;table style="border-collapse: collapse; margin-top: 20px;"&gt;&lt;tr&gt;&lt;td width="597" align="left" colspan="7" style="border-top: 1px solid #000000;" height="17"&gt;&lt;b&gt;COMMON STOCK ACTIVITY&lt;/b&gt;&lt;/td&gt;&lt;/tr&gt;&lt;tr&gt;&lt;td width="597" align="left" height="17" colspan="7"&gt;&lt;i&gt;&amp;#160;&lt;/i&gt;&lt;/td&gt;&lt;/tr&gt;&lt;tr&gt;&lt;td height="14" style="border-bottom: 1px solid #000000;" align="left" width="264"&gt;&amp;#160;&lt;/td&gt;&lt;td height="14" style="border-bottom: 1px solid #000000;" align="left" width="22"&gt;&amp;#160;&lt;/td&gt;&lt;td height="14" style="border-bottom: 1px solid #000000;" align="center" width="89"&gt;2009&amp;#160;&lt;/td&gt;&lt;td height="14" style="border-bottom: 1px solid #000000;" align="left" width="22"&gt;&amp;#160;&lt;/td&gt;&lt;td height="14" style="border-bottom: 1px solid #000000;" align="center" width="89"&gt;2008&amp;#160;&lt;/td&gt;&lt;td height="14" style="border-bottom: 1px solid #000000;" align="left" width="22"&gt;&amp;#160;&lt;/td&gt;&lt;td height="14" style="border-bottom: 1px solid #000000;" align="center" width="89"&gt;2007&amp;#160;&lt;/td&gt;&lt;/tr&gt;&lt;tr&gt;&lt;td height="17" style="border-top: 1px solid #000000;" align="left" width="264"&gt;Common shares outstanding, January 1&lt;/td&gt;&lt;td height="17" style="border-top: 1px solid #000000;" align="left" width="22"&gt;&amp;#160;&lt;/td&gt;&lt;td height="17" style="border-top: 1px solid #000000;" align="right" width="89"&gt;&amp;#160;243,324,281&amp;#160;&lt;/td&gt;&lt;td height="17" style="border-top: 1px solid #000000;" align="left" width="22"&gt;&amp;#160;&lt;/td&gt;&lt;td height="17" style="border-top: 1px solid #000000;" align="right" width="89"&gt;&amp;#160;261,214,009&amp;#160;&lt;/td&gt;&lt;td height="17" style="border-top: 1px solid #000000;" align="left" width="22"&gt;&amp;#160;&lt;/td&gt;&lt;td height="17" style="border-top: 1px solid #000000;" align="right" width="89"&gt;&amp;#160;262,005,690&amp;#160;&lt;/td&gt;&lt;/tr&gt;&lt;tr&gt;&lt;td height="17" width="264" align="left"&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;Savings plan issuance&lt;/td&gt;&lt;td height="17" width="22" align="left"&gt;&amp;#160;&lt;/td&gt;&lt;td height="17" width="89" align="right"&gt;&amp;#160;1,021,023&amp;#160;&lt;/td&gt;&lt;td height="17" width="22" align="left"&gt;&amp;#160;&lt;/td&gt;&lt;td height="17" width="89" align="right"&gt;&amp;#160;-&amp;#160;&lt;/td&gt;&lt;td height="17" width="22" align="left"&gt;&amp;#160;&lt;/td&gt;&lt;td height="17" width="89" align="right"&gt;&amp;#160;268,178&amp;#160;&lt;/td&gt;&lt;/tr&gt;&lt;tr&gt;&lt;td height="17" width="264" align="left"&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;Shares released from ESOP&lt;/td&gt;&lt;td height="17" width="22" align="left"&gt;&amp;#160;&lt;/td&gt;&lt;td height="17" width="89" align="right"&gt;&amp;#160;309,023&amp;#160;&lt;/td&gt;&lt;td height="17" width="22" align="left"&gt;&amp;#160;&lt;/td&gt;&lt;td height="17" width="89" align="right"&gt;&amp;#160;310,850&amp;#160;&lt;/td&gt;&lt;td height="17" width="22" align="left"&gt;&amp;#160;&lt;/td&gt;&lt;td height="17" width="89" align="right"&gt;&amp;#160;195,720&amp;#160;&lt;/td&gt;&lt;/tr&gt;&lt;tr&gt;&lt;td height="17" width="264" align="left"&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;Stock options exercised&lt;/td&gt;&lt;td height="17" width="22" align="left"&gt;&amp;#160;&lt;/td&gt;&lt;td height="17" width="89" align="right"&gt;&amp;#160;1,835,184&amp;#160;&lt;/td&gt;&lt;td height="17" width="22" align="left"&gt;&amp;#160;&lt;/td&gt;&lt;td height="17" width="89" align="right"&gt;&amp;#160;683,858&amp;#160;&lt;/td&gt;&lt;td height="17" width="22" align="left"&gt;&amp;#160;&lt;/td&gt;&lt;td height="17" width="89" align="right"&gt;&amp;#160;1,245,696&amp;#160;&lt;/td&gt;&lt;/tr&gt;&lt;tr&gt;&lt;td height="17" width="264" align="left"&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;Restricted stock issuances&lt;/td&gt;&lt;td height="17" width="22" align="left"&gt;&amp;#160;&lt;/td&gt;&lt;td height="17" width="89" align="right"&gt;&amp;#160;37,233&amp;#160;&lt;/td&gt;&lt;td height="17" width="22" align="left"&gt;&amp;#160;&lt;/td&gt;&lt;td height="17" width="89" align="right"&gt;&amp;#160;4,002&amp;#160;&lt;/td&gt;&lt;td height="17" width="22" align="left"&gt;&amp;#160;&lt;/td&gt;&lt;td height="17" width="89" align="right"&gt;&amp;#160;803,706&amp;#160;&lt;/td&gt;&lt;/tr&gt;&lt;tr&gt;&lt;td height="17" width="264" align="left"&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;Common stock investment plan(1)&lt;/td&gt;&lt;td height="17" width="22" align="left"&gt;&amp;#160;&lt;/td&gt;&lt;td height="17" width="89" align="right"&gt;&amp;#160;381,167&amp;#160;&lt;/td&gt;&lt;td height="17" width="22" align="left"&gt;&amp;#160;&lt;/td&gt;&lt;td height="17" width="89" align="right"&gt;&amp;#160;1,508&amp;#160;&lt;/td&gt;&lt;td height="17" width="22" align="left"&gt;&amp;#160;&lt;/td&gt;&lt;td height="17" width="89" align="right"&gt;&amp;#160;95,499&amp;#160;&lt;/td&gt;&lt;/tr&gt;&lt;tr&gt;&lt;td height="17" width="264" align="left"&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;Shares repurchased&lt;/td&gt;&lt;td height="17" width="22" align="left"&gt;&amp;#160;&lt;/td&gt;&lt;td height="17" width="89" align="right"&gt;&amp;#160;(396,046)&lt;/td&gt;&lt;td height="17" width="22" align="left"&gt;&amp;#160;&lt;/td&gt;&lt;td height="17" width="89" align="right"&gt;&amp;#160;(18,841,287)&lt;/td&gt;&lt;td height="17" width="22" align="left"&gt;&amp;#160;&lt;/td&gt;&lt;td height="17" width="89" align="right"&gt;&amp;#160;(3,349,771)&lt;/td&gt;&lt;/tr&gt;&lt;tr&gt;&lt;td height="17" width="264" align="left"&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;Shares forfeited and other&lt;/td&gt;&lt;td height="17" style="border-bottom: 1px solid #000000;" align="left" width="22"&gt;&amp;#160;&lt;/td&gt;&lt;td height="17" style="border-bottom: 1px solid #000000;" align="right" width="89"&gt;&amp;#160;(4,000)&lt;/td&gt;&lt;td height="17" style="border-bottom: 1px solid #000000;" align="left" width="22"&gt;&amp;#160;&lt;/td&gt;&lt;td height="17" style="border-bottom: 1px solid #000000;" align="right" width="89"&gt;&amp;#160;(48,659)&lt;/td&gt;&lt;td height="17" style="border-bottom: 1px solid #000000;" align="left" width="22"&gt;&amp;#160;&lt;/td&gt;&lt;td height="17" style="border-bottom: 1px solid #000000;" align="right" width="89"&gt;&amp;#160;(50,709)&lt;/td&gt;&lt;/tr&gt;&lt;tr&gt;&lt;td height="18" style="border-bottom: 3px solid #000000;" align="left" width="264"&gt;Common shares outstanding, December 31&lt;/td&gt;&lt;td height="18" style="border-top: 1px solid #000000;border-bottom: 3px solid #000000;" align="left" width="22"&gt;&amp;#160;&lt;/td&gt;&lt;td height="18" style="border-top: 1px solid #000000;border-bottom: 3px solid #000000;" align="right" width="89"&gt;&amp;#160;246,507,865&amp;#160;&lt;/td&gt;&lt;td height="18" style="border-top: 1px solid #000000;border-bottom: 3px solid #000000;" align="left" width="22"&gt;&amp;#160;&lt;/td&gt;&lt;td height="18" style="border-top: 1px solid #000000;border-bottom: 3px solid #000000;" align="right" width="89"&gt;&amp;#160;243,324,281&amp;#160;&lt;/td&gt;&lt;td height="18" style="border-top: 1px solid #000000;border-bottom: 3px solid #000000;" align="left" width="22"&gt;&amp;#160;&lt;/td&gt;&lt;td height="18" style="border-top: 1px solid #000000;border-bottom: 3px solid #000000;" align="right" width="89"&gt;&amp;#160;261,214,009&amp;#160;&lt;/td&gt;&lt;/tr&gt;&lt;tr&gt;&lt;td width="597" align="left" colspan="7" style="border-top: 3px solid #000000;" height="18"&gt;&lt;i&gt;(1) Participants in the Direct Stock Purchase Plan may reinvest dividends to purchase newly issued shares.&lt;/i&gt;&lt;/td&gt;&lt;/tr&gt;&lt;/table&gt;&lt;p&gt;Our board of directors has the discretion to determine the payment and amount of future dividends. &lt;br /&gt;Common Stock Repurchase Program&lt;br /&gt;On September 11, 2007, our board of directors authorized the repurchase of additional shares of our common stock provided that the amounts expended for such purposes did not exceed the greater of $2 billion or amounts expended to purchase no more than 40 million shares. Purchases may include open-market and negotiated transactions, structured purchase arrangements, and tender offers.&lt;br /&gt;In April 2008, we entered into a Collared Accelerated Share Acquisition Program under which we prepaid $1 billion to repurchase shares of our common stock to be delivered later in 2008 in a share forward transaction. Our outstanding shares used to calculate earnings per share were reduced by the number of shares repurchased when they were delivered to us, and the $1 billion purchase price was recorded as a reduction in shareholders&amp;#8217; equity upon its prepayment. We received 18,416,241 shares under the program during 2008 based on a final weighted average price of $54.30 per share.&lt;br /&gt;This share repurchase program is unrelated to share-based compensation as described in Note 10.&lt;/p&gt;&lt;/div&gt;</NonNumbericText>
          <NonNumericTextHeader>We are authorized to issue 750,000,000 shares of no-par-value common stock. In addition, we are authorized to issue 50,000,000 shares of preferred stock having</NonNumericTextHeader>
          <FootnoteIndexer />
          <hasSegments>false</hasSegments>
          <hasScenarios>false</hasScenarios>
        </Cell>
      </Cells>
      <ElementDefenition>No definition available.</ElementDefenition>
      <ElementReferences>No authoritative reference available.</ElementReferences>
      <IsTotalLabel>false</IsTotalLabel>
    </Row>
  </Rows>
  <Footnotes />
  <ComparabilityReport>false</ComparabilityReport>
  <NumberOfCols>1</NumberOfCols>
  <NumberOfRows>2</NumberOfRows>
  <HasScenarios>false</HasScenarios>
  <MonetaryRoundingLevel>UnKnown</MonetaryRoundingLevel>
  <SharesRoundingLevel>UnKnown</SharesRoundingLevel>
  <PerShareRoundingLevel>UnKnown</PerShareRoundingLevel>
  <HasPureData>false</HasPureData>
  <SharesShouldBeRounded>true</SharesShouldBeRounded>
</InstanceReport>
