<?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>4034 - Disclosure - INVESTMENT OPERATIONS (Details 5)</ReportLongName><DisplayLabelColumn>true</DisplayLabelColumn><ShowElementNames>false</ShowElementNames><RoundingOption /><HasEmbeddedReports>false</HasEmbeddedReports><Columns><Column FlagID="0"><Id>1</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><CurrencyCode>USD</CurrencyCode><FootnoteIndexer /><hasSegments>false</hasSegments><hasScenarios>false</hasScenarios><MCU><KeyName /><CurrencySymbol /><contextRef><ContextID>D2013Q2YTD_RedMountainLLCMember</ContextID><EntitySchema>http://www.sec.gov/CIK</EntitySchema><EntityValue>0000355429</EntityValue><PeriodDisplayName /><PeriodType>duration</PeriodType><PeriodStartDate>2013-01-01T00:00:00</PeriodStartDate><PeriodEndDate>2013-06-30T00:00:00</PeriodEndDate><Segments /><Scenarios /></contextRef><UPS><UnitProperty><UnitID>Pure</UnitID><UnitType>Standard</UnitType><StandardMeasure><MeasureSchema>http://www.xbrl.org/2003/instance</MeasureSchema><MeasureValue>pure</MeasureValue><MeasureNamespace>xbrli</MeasureNamespace><MeasureDescription /><MeasureType /></StandardMeasure><MultiplyMeasures><Measure><MeasureSchema /><MeasureValue /><MeasureNamespace /><MeasureDescription /><MeasureType /></Measure><Measure><MeasureSchema /><MeasureValue /><MeasureNamespace /><MeasureDescription /><MeasureType /></Measure></MultiplyMeasures><NumeratorMeasure><MeasureSchema /><MeasureValue /><MeasureNamespace /><MeasureDescription /><MeasureType /></NumeratorMeasure><DenominatorMeasure><MeasureSchema /><MeasureValue /><MeasureNamespace /><MeasureDescription /><MeasureType /></DenominatorMeasure><Scale>0</Scale></UnitProperty><UnitProperty><UnitID>Item</UnitID><UnitType>Standard</UnitType><StandardMeasure><MeasureSchema>http://www.protective.com/20130630</MeasureSchema><MeasureValue>item</MeasureValue><MeasureNamespace>pl</MeasureNamespace><MeasureDescription /><MeasureType /></StandardMeasure><MultiplyMeasures><Measure><MeasureSchema /><MeasureValue /><MeasureNamespace /><MeasureDescription /><MeasureType /></Measure><Measure><MeasureSchema /><MeasureValue /><MeasureNamespace /><MeasureDescription /><MeasureType /></Measure></MultiplyMeasures><NumeratorMeasure><MeasureSchema /><MeasureValue /><MeasureNamespace /><MeasureDescription /><MeasureType /></NumeratorMeasure><DenominatorMeasure><MeasureSchema /><MeasureValue /><MeasureNamespace /><MeasureDescription /><MeasureType /></DenominatorMeasure><Scale>0</Scale></UnitProperty><UnitProperty><UnitID>USD</UnitID><UnitType>Standard</UnitType><StandardMeasure><MeasureSchema>http://www.xbrl.org/2003/iso4217</MeasureSchema><MeasureValue>USD</MeasureValue><MeasureNamespace>iso4217</MeasureNamespace><MeasureDescription /><MeasureType /></StandardMeasure><MultiplyMeasures><Measure><MeasureSchema /><MeasureValue /><MeasureNamespace /><MeasureDescription /><MeasureType /></Measure><Measure><MeasureSchema /><MeasureValue /><MeasureNamespace /><MeasureDescription /><MeasureType /></Measure></MultiplyMeasures><NumeratorMeasure><MeasureSchema /><MeasureValue /><MeasureNamespace /><MeasureDescription /><MeasureType /></NumeratorMeasure><DenominatorMeasure><MeasureSchema /><MeasureValue /><MeasureNamespace /><MeasureDescription /><MeasureType /></DenominatorMeasure><Scale>0</Scale></UnitProperty></UPS><CurrencyCode /><OriginalCurrencyCode /></MCU><CurrencySymbol>$</CurrencySymbol><Labels><Label Key="CalendarSupplement" Id="0" Label="6 Months Ended" /><Label Key="Calendar" Id="1" Label="Jun. 30, 2013" /><Label Key="" Id="2" Label="item" /></Labels></Column></Columns><Rows><Row FlagID="0"><Id>1</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><Level>0</Level><ElementName /><ElementPrefix /><IsBaseElement>true</IsBaseElement><BalanceType /><PeriodType /><IsReportTitle>false</IsReportTitle><IsSegmentTitle>true</IsSegmentTitle><IsCalendarTitle>false</IsCalendarTitle><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><PreferredLabelRole /><FootnoteIndexer /><Cells><Cell FlagID="0" ContextID="" UnitID=""><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText /><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell></Cells><OriginalInstanceReportColumn FlagID="0"><Id>1</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><CurrencyCode>USD</CurrencyCode><FootnoteIndexer /><hasSegments>true</hasSegments><hasScenarios>false</hasScenarios><MCU><KeyName /><CurrencySymbol /><contextRef><ContextID>D2013Q2YTD_RedMountainLLCMember</ContextID><EntitySchema>http://www.sec.gov/CIK</EntitySchema><EntityValue>0000355429</EntityValue><PeriodDisplayName /><PeriodType>duration</PeriodType><PeriodStartDate>2013-01-01T00:00:00</PeriodStartDate><PeriodEndDate>2013-06-30T00:00:00</PeriodEndDate><Segments><anyType xsi:type="Segment"><IsDefaultForEntity>false</IsDefaultForEntity><Name /><IsFromEntityGroup>false</IsFromEntityGroup><ValueName>Red Mountain</ValueName><ValueType>us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis</ValueType><Namespace>xbrldi</Namespace><Schema>http://xbrl.org/2006/xbrldi</Schema><DimensionInfo><Id>pl_RedMountainLLCMember</Id><dimensionId>us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis</dimensionId><type>explicitMember</type></DimensionInfo></anyType></Segments><Scenarios /></contextRef><UPS><UnitProperty><UnitID>Pure</UnitID><UnitType>Standard</UnitType><StandardMeasure><MeasureSchema>http://www.xbrl.org/2003/instance</MeasureSchema><MeasureValue>pure</MeasureValue><MeasureNamespace>xbrli</MeasureNamespace><MeasureDescription /><MeasureType /></StandardMeasure><MultiplyMeasures><Measure><MeasureSchema /><MeasureValue /><MeasureNamespace /><MeasureDescription /><MeasureType /></Measure><Measure><MeasureSchema /><MeasureValue /><MeasureNamespace /><MeasureDescription /><MeasureType /></Measure></MultiplyMeasures><NumeratorMeasure><MeasureSchema /><MeasureValue /><MeasureNamespace /><MeasureDescription /><MeasureType /></NumeratorMeasure><DenominatorMeasure><MeasureSchema /><MeasureValue /><MeasureNamespace /><MeasureDescription /><MeasureType /></DenominatorMeasure><Scale>0</Scale></UnitProperty><UnitProperty><UnitID>Item</UnitID><UnitType>Standard</UnitType><StandardMeasure><MeasureSchema>http://www.protective.com/20130630</MeasureSchema><MeasureValue>item</MeasureValue><MeasureNamespace>pl</MeasureNamespace><MeasureDescription /><MeasureType /></StandardMeasure><MultiplyMeasures><Measure><MeasureSchema /><MeasureValue /><MeasureNamespace /><MeasureDescription /><MeasureType /></Measure><Measure><MeasureSchema /><MeasureValue /><MeasureNamespace /><MeasureDescription /><MeasureType /></Measure></MultiplyMeasures><NumeratorMeasure><MeasureSchema /><MeasureValue /><MeasureNamespace /><MeasureDescription /><MeasureType /></NumeratorMeasure><DenominatorMeasure><MeasureSchema /><MeasureValue /><MeasureNamespace /><MeasureDescription /><MeasureType /></DenominatorMeasure><Scale>0</Scale></UnitProperty><UnitProperty><UnitID>USD</UnitID><UnitType>Standard</UnitType><StandardMeasure><MeasureSchema>http://www.xbrl.org/2003/iso4217</MeasureSchema><MeasureValue>USD</MeasureValue><MeasureNamespace>iso4217</MeasureNamespace><MeasureDescription /><MeasureType /></StandardMeasure><MultiplyMeasures><Measure><MeasureSchema /><MeasureValue /><MeasureNamespace /><MeasureDescription /><MeasureType /></Measure><Measure><MeasureSchema /><MeasureValue /><MeasureNamespace /><MeasureDescription /><MeasureType /></Measure></MultiplyMeasures><NumeratorMeasure><MeasureSchema /><MeasureValue /><MeasureNamespace /><MeasureDescription /><MeasureType /></NumeratorMeasure><DenominatorMeasure><MeasureSchema /><MeasureValue /><MeasureNamespace /><MeasureDescription /><MeasureType /></DenominatorMeasure><Scale>0</Scale></UnitProperty></UPS><CurrencyCode /><OriginalCurrencyCode /></MCU><CurrencySymbol>$</CurrencySymbol><Labels><Label Key="Calendar" Id="1" Label="1/1/2013 - 6/30/2013" /><Label Key="" Id="2" Label="item" /></Labels></OriginalInstanceReportColumn><ElementDataType>na</ElementDataType><SimpleDataType>na</SimpleDataType><IsTotalLabel>false</IsTotalLabel><UnitID>0</UnitID><Label>Red Mountain</Label></Row><Row FlagID="0"><Id>2</Id><IsAbstractGroupTitle>true</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><Level>3</Level><ElementName>us-gaap_VariableInterestEntityLineItems</ElementName><ElementPrefix>us-gaap_</ElementPrefix><IsBaseElement>true</IsBaseElement><BalanceType>na</BalanceType><PeriodType>duration</PeriodType><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsCalendarTitle>false</IsCalendarTitle><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><PreferredLabelRole>terseLabel</PreferredLabelRole><FootnoteIndexer /><Cells><Cell FlagID="0" ContextID="" UnitID=""><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText /><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell></Cells><ElementDataType>xbrli:stringItemType</ElementDataType><SimpleDataType>string</SimpleDataType><IsTotalLabel>false</IsTotalLabel><UnitID>0</UnitID><Label>Variable Interest Entities</Label></Row><Row FlagID="0"><Id>3</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><Level>4</Level><ElementName>pl_NumberOfWhollyOwnedSubsidiariesWhichWereDeterminedToBeVIE</ElementName><ElementPrefix>pl_</ElementPrefix><IsBaseElement>false</IsBaseElement><BalanceType>na</BalanceType><PeriodType>instant</PeriodType><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsCalendarTitle>false</IsCalendarTitle><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><PreferredLabelRole>terseLabel</PreferredLabelRole><FootnoteIndexer /><Cells><Cell FlagID="0" ContextID="I2013Q2_RedMountainLLCMember" UnitID="Item"><Id>1</Id><IsNumeric>true</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>1</NumericAmount><RoundedNumericAmount>1</RoundedNumericAmount><NonNumbericText /><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell></Cells><ElementDataType>xbrli:integerItemType</ElementDataType><SimpleDataType>integer</SimpleDataType><ElementDefenition>Represents the number of wholly owned subsidiaries which were determined to be variable interest entities.</ElementDefenition><ElementReferences>No definition available.</ElementReferences><IsTotalLabel>false</IsTotalLabel><UnitID>256</UnitID><Label>Number of wholly owned subsidiaries that were determined to be VIEs</Label></Row><Row FlagID="0"><Id>4</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><Level>4</Level><ElementName>us-gaap_VariableInterestEntityOwnershipPercentage</ElementName><ElementPrefix>us-gaap_</ElementPrefix><IsBaseElement>true</IsBaseElement><BalanceType>na</BalanceType><PeriodType>duration</PeriodType><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsCalendarTitle>false</IsCalendarTitle><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><PreferredLabelRole>terseLabel</PreferredLabelRole><FootnoteIndexer /><Cells><Cell FlagID="0" ContextID="D2013Q2YTD_RedMountainLLCMember" UnitID="Pure"><Id>1</Id><IsNumeric>true</IsNumeric><IsRatio>true</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>1.00</NumericAmount><RoundedNumericAmount>1.00</RoundedNumericAmount><NonNumbericText /><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell></Cells><ElementDataType>num:percentItemType</ElementDataType><SimpleDataType>pure</SimpleDataType><ElementDefenition>Percentage of the Variable Interest Entity's (VIE) voting interest owned by (or beneficial interest in) the reporting entity (directly or indirectly).</ElementDefenition><ElementReferences>Reference 1: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 810

 -SubTopic 10

 -Section 50

 -Paragraph 5A

 -Subparagraph (d)

 -URI http://asc.fasb.org/extlink&amp;oid=7880789&amp;loc=SL6759159-111685



</ElementReferences><IsTotalLabel>false</IsTotalLabel><UnitID>0</UnitID><Label>Ownership through an affiliate (as a percent)</Label></Row><Row FlagID="0"><Id>5</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><Level>4</Level><ElementName>us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount</ElementName><ElementPrefix>us-gaap_</ElementPrefix><IsBaseElement>true</IsBaseElement><BalanceType>credit</BalanceType><PeriodType>instant</PeriodType><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsCalendarTitle>false</IsCalendarTitle><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><PreferredLabelRole>terseLabel</PreferredLabelRole><FootnoteIndexer /><Cells><Cell FlagID="0" ContextID="I2013Q2_RedMountainLLCMember" UnitID="USD"><Id>1</Id><IsNumeric>true</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>10000</NumericAmount><RoundedNumericAmount>10000</RoundedNumericAmount><NonNumbericText /><FootnoteIndexer /><CurrencyCode>USD</CurrencyCode><CurrencySymbol>$</CurrencySymbol><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>true</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell></Cells><ElementDataType>xbrli:monetaryItemType</ElementDataType><SimpleDataType>monetary</SimpleDataType><ElementDefenition>The reporting entity's maximum amount of exposure to loss as a result of its involvement with the Variable Interest Entity (VIE).</ElementDefenition><ElementReferences>Reference 1: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 810

 -SubTopic 10

 -Section 50

 -Paragraph 4

 -Subparagraph b

 -URI http://asc.fasb.org/extlink&amp;oid=7880789&amp;loc=d3e5728-111685



Reference 2: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 810

 -SubTopic 10

 -Section 50

 -Paragraph 6

 -Subparagraph (c)

 -URI http://asc.fasb.org/extlink&amp;oid=7880789&amp;loc=d3e5747-111685



Reference 3: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name FASB Staff Position (FSP)

 -Number FAS140-4/FIN46(R)

 -Paragraph C6

 -Subparagraph b

 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.  This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.



</ElementReferences><IsTotalLabel>false</IsTotalLabel><UnitID>2</UnitID><Label>Risk of loss related to the VIE limited to the entity's investment</Label></Row></Rows><Footnotes /><IsEquityReport>false</IsEquityReport><ReportName>INVESTMENT OPERATIONS (Details 5) (Red Mountain, USD $)</ReportName><MonetaryRoundingLevel>NoRounding</MonetaryRoundingLevel><SharesRoundingLevel>UnKnown</SharesRoundingLevel><PerShareRoundingLevel>UnKnown</PerShareRoundingLevel><ExchangeRateRoundingLevel>UnKnown</ExchangeRateRoundingLevel><HasCustomUnits>true</HasCustomUnits><IsEmbedReport>false</IsEmbedReport><IsMultiCurrency>false</IsMultiCurrency><ReportType>Sheet</ReportType><RoleURI>http://www.protective.com/role/DisclosureInvestmentOperationsDetails5</RoleURI><NumberOfCols>1</NumberOfCols><NumberOfRows>5</NumberOfRows></InstanceReport>
