<?xml version="1.0" encoding="us-ascii"?><InstanceReport xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"><Version>2.4.0.8</Version><ReportLongName>117 - Disclosure - Equity</ReportLongName><DisplayLabelColumn>true</DisplayLabelColumn><ShowElementNames>false</ShowElementNames><RoundingOption /><HasEmbeddedReports>false</HasEmbeddedReports><Columns><Column FlagID="0"><Id>1</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

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&lt;div style="TEXT-INDENT: 0pt; DISPLAY: block; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="justify"&gt;&lt;font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt; FONT-WEIGHT: bold"&gt;
Note 9.&amp;#xA0;&amp;#xA0;Equity&lt;/font&gt;&lt;/div&gt;
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&lt;div style="TEXT-INDENT: 18pt; DISPLAY: block; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="justify"&gt;&lt;font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt"&gt;For
the six months ended June 30, 2013, equity related transactions
were as follows:&lt;/font&gt;&lt;/div&gt;
&lt;div style="TEXT-INDENT: 0pt; DISPLAY: block"&gt;&lt;br /&gt;&lt;/div&gt;
&lt;div&gt;
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&lt;div style="TEXT-ALIGN: center"&gt;&lt;font style="font-family:Symbol, serif"&gt;&lt;font style="LETTER-SPACING: 9pt"&gt;&amp;#xA0;&amp;#xA0;&amp;#xA0;&lt;/font&gt;&lt;font style="DISPLAY: inline; FONT-FAMILY: Times New Roman"&gt;&amp;#x25CF;&lt;/font&gt;&amp;#xA0;&amp;#xA0;&lt;/font&gt;&lt;/div&gt;
&lt;/td&gt;
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&lt;div style="TEXT-INDENT: 0pt; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="justify"&gt;&lt;font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt"&gt;In
January 2013, 125,000 shares of common stock were sold and 975
additional commitment shares were issued to Lincoln Park under the
$1.5 million purchase agreement for net proceeds of
$142,400.&lt;/font&gt;&lt;/div&gt;
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&lt;div&gt;
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&lt;div style="TEXT-ALIGN: center"&gt;&lt;font style="font-family:Symbol, serif"&gt;&lt;font style="LETTER-SPACING: 9pt"&gt;&amp;#xA0;&amp;#xA0;&amp;#xA0;&lt;/font&gt;&lt;font style="DISPLAY: inline; FONT-FAMILY: Times New Roman"&gt;&amp;#x25CF;&lt;/font&gt;&amp;#xA0;&amp;#xA0;&lt;/font&gt;&lt;/div&gt;
&lt;/td&gt;
&lt;td&gt;
&lt;div style="TEXT-INDENT: 0pt; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="justify"&gt;&lt;font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt"&gt;365,263
shares of common stock were issued in connection with the
conversion of the January 2013 and July 2012 Notes (see Note
7).&lt;/font&gt;&lt;/div&gt;
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&lt;/tr&gt;
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&lt;div style="TEXT-ALIGN: center"&gt;&lt;font style="font-family:Symbol, serif"&gt;&lt;font style="LETTER-SPACING: 9pt"&gt;&amp;#xA0;&amp;#xA0;&amp;#xA0;&lt;/font&gt;&lt;font style="DISPLAY: inline; FONT-FAMILY: Times New Roman"&gt;&amp;#x25CF;&lt;/font&gt;&amp;#xA0;&amp;#xA0;&lt;/font&gt;&lt;/div&gt;
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&lt;div style="TEXT-INDENT: 0pt; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="justify"&gt;&lt;font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt"&gt;In
February 2013, Opexa sold an aggregate of 167,618 shares of common
stock under the ATM Agreement for gross proceeds of
$536,417.&lt;/font&gt;&lt;/div&gt;
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&lt;div style="TEXT-INDENT: 0pt; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="justify"&gt;&lt;font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt"&gt;On
February 11, 2013, Opexa sold an aggregate of 1,083,334 units in a
registered offering, with each unit consisting of one share of
common stock and a warrant to purchase half (0.5) a share of common
stock, at a price of $3.00 per unit, for gross proceeds of
$3,250,002. The shares of common stock and warrants were
immediately separable and were issued separately such that no units
were issued. The warrants are exercisable immediately upon
issuance, have a four-year term and an exercise price of $3.00 per
share. A fee of 6.0% of the gross proceeds was paid to the
placement agent.&lt;/font&gt;&lt;/div&gt;
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the six months ended June 30, 2013, $350,530 was netted against
additional paid in capital as stock offering costs.&lt;/font&gt;&lt;/div&gt;
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