<?xml version="1.0" encoding="us-ascii"?><InstanceReport xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"><Version>2.2.0.25</Version><hasSegments>false</hasSegments><hasScenarios>false</hasScenarios><ReportLongName>006030 - Disclosure - FEDERAL FUNDS SOLD AND SHORT-TERM INVESTMENTS</ReportLongName><DisplayLabelColumn>true</DisplayLabelColumn><ShowElementNames>false</ShowElementNames><RoundingOption /><HasEmbeddedReports>false</HasEmbeddedReports><Columns><Column><Id>1</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelColumn>false</LabelColumn><CurrencyCode>USD</CurrencyCode><FootnoteIndexer /><hasSegments>false</hasSegments><hasScenarios>false</hasScenarios><MCU><KeyName>1/1/2010 - 12/31/2010
USD ($)

USD ($) / shares

</KeyName><CurrencySymbol>$</CurrencySymbol><contextRef><ContextID>c00035</ContextID><EntitySchema>http://www.sec.gov/CIK</EntitySchema><EntityValue>0000106926</EntityValue><PeriodDisplayName /><PeriodType>duration</PeriodType><PeriodStartDate>2010-01-01T00:00:00</PeriodStartDate><PeriodEndDate>2010-12-31T00:00:00</PeriodEndDate><Segments /><Scenarios /></contextRef><UPS><UnitProperty><UnitID>u000</UnitID><UnitType>Standard</UnitType><StandardMeasure><MeasureSchema>http://www.xbrl.org/2003/iso4217</MeasureSchema><MeasureValue>USD</MeasureValue><MeasureNamespace>iso4217</MeasureNamespace></StandardMeasure><Scale>0</Scale></UnitProperty><UnitProperty><UnitID>u002</UnitID><UnitType>Divide</UnitType><NumeratorMeasure><MeasureSchema>http://www.xbrl.org/2003/iso4217</MeasureSchema><MeasureValue>USD</MeasureValue><MeasureNamespace>iso4217</MeasureNamespace></NumeratorMeasure><DenominatorMeasure><MeasureSchema>http://www.xbrl.org/2003/instance</MeasureSchema><MeasureValue>shares</MeasureValue><MeasureNamespace>xbrli</MeasureNamespace></DenominatorMeasure><Scale>0</Scale></UnitProperty><UnitProperty><UnitID>u001</UnitID><UnitType>Standard</UnitType><StandardMeasure><MeasureSchema>http://www.xbrl.org/2003/instance</MeasureSchema><MeasureValue>shares</MeasureValue><MeasureNamespace>xbrli</MeasureNamespace></StandardMeasure><Scale>0</Scale></UnitProperty></UPS><CurrencyCode>USD</CurrencyCode><OriginalCurrencyCode>USD</OriginalCurrencyCode></MCU><CurrencySymbol>$</CurrencySymbol><Labels><Label Id="1" Label="12 Months Ended" /><Label Id="2" Label="Dec. 31, 2010" /></Labels></Column></Columns><Rows><Row><Id>2</Id><IsAbstractGroupTitle>true</IsAbstractGroupTitle><Level>0</Level><ElementName>wtny_NotesToFinancialStatementsAbstract</ElementName><ElementPrefix>wtny</ElementPrefix><IsBaseElement>false</IsBaseElement><BalanceType>na</BalanceType><PeriodType>duration</PeriodType><ShortDefinition>No definition available.</ShortDefinition><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsSubReportEnd>false</IsSubReportEnd><IsCalendarTitle>false</IsCalendarTitle><IsTuple>false</IsTuple><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><PreferredLabelRole /><FootnoteIndexer /><Cells><Cell><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText /><NonNumericTextHeader /><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat><hasSegments>false</hasSegments><hasScenarios>false</hasScenarios></Cell></Cells><OriginalInstanceReportColumns /><Unit>Other</Unit><ElementDataType>xbrli:stringItemType</ElementDataType><SimpleDataType>string</SimpleDataType><ElementDefenition>No definition available.</ElementDefenition><IsTotalLabel>false</IsTotalLabel><IsEPS>false</IsEPS><Label>Notes to Financial Statements [Abstract]</Label></Row><Row><Id>3</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><Level>0</Level><ElementName>wtny_FederalFundsSoldAndShortTermInvestmentsTextBlock</ElementName><ElementPrefix>wtny</ElementPrefix><IsBaseElement>false</IsBaseElement><BalanceType>na</BalanceType><PeriodType>duration</PeriodType><ShortDefinition>No definition available.</ShortDefinition><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsSubReportEnd>false</IsSubReportEnd><IsCalendarTitle>false</IsCalendarTitle><IsTuple>false</IsTuple><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><PreferredLabelRole /><FootnoteIndexer /><Cells><Cell><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText>&lt;div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt" align="left"&gt;&lt;font style="DISPLAY: inline; FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman"&gt;NOTE 4&lt;/font&gt;&lt;/div&gt;&lt;div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt" align="left"&gt;&lt;font style="DISPLAY: inline; FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman"&gt;FEDERAL FUNDS SOLD AND SHORT-TERM INVESTMENTS&lt;/font&gt;&lt;/div&gt;&lt;div style="DISPLAY: block; TEXT-INDENT: 0pt"&gt;&lt;br /&gt;&lt;/div&gt;&lt;div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 36pt; MARGIN-RIGHT: 0pt" align="left"&gt;&lt;font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman"&gt;The balance of federal funds sold and short-term investments included the following.&lt;/font&gt;&lt;/div&gt;&lt;div align="left"&gt;&lt;table style="FONT-SIZE: 10pt; FONT-FAMILY: times new roman" cellspacing="0" cellpadding="0" width="85%"&gt;&lt;tr&gt;&lt;td style="BORDER-BOTTOM: black 4px double" valign="bottom" width="76%"&gt;&lt;font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;&amp;#160; &lt;/font&gt;&lt;/td&gt;&lt;td style="BORDER-BOTTOM: black 4px double" valign="bottom" align="right" width="1%"&gt;&lt;font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;&amp;#160;&lt;/font&gt;&lt;/td&gt;&lt;td style="BORDER-BOTTOM: black 4px double; TEXT-ALIGN: center" valign="bottom" width="17%" colspan="7"&gt;&lt;div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt; TEXT-ALIGN: center"&gt;&lt;font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;December 31&lt;/font&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;&lt;tr&gt;&lt;td style="BORDER-BOTTOM: black 2px solid" valign="bottom" align="left" width="76%"&gt;&lt;div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt" align="left"&gt;&lt;font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-STYLE: italic; FONT-FAMILY: times new roman"&gt;(in thousands)&lt;/font&gt;&lt;/div&gt;&lt;/td&gt;&lt;td style="BORDER-BOTTOM: black 2px solid" valign="bottom" align="right" width="1%"&gt;&lt;font style="DISPLAY: inline; FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;&amp;#160;&lt;/font&gt;&lt;/td&gt;&lt;td style="BORDER-BOTTOM: black 2px solid; TEXT-ALIGN: center" valign="bottom" width="7%" colspan="2"&gt;&lt;div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt; TEXT-ALIGN: center"&gt;&lt;font style="DISPLAY: inline; FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;2010&lt;/font&gt;&lt;/div&gt;&lt;/td&gt;&lt;td style="BORDER-BOTTOM: black 2px solid; TEXT-ALIGN: left" valign="bottom" nowrap="nowrap" width="1%"&gt;&lt;font style="DISPLAY: inline; FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;&amp;#160;&lt;/font&gt;&lt;/td&gt;&lt;td style="BORDER-BOTTOM: black 2px solid" valign="bottom" align="right" width="1%"&gt;&lt;font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;&amp;#160;&lt;/font&gt;&lt;/td&gt;&lt;td style="BORDER-BOTTOM: black 2px solid; TEXT-ALIGN: center" valign="bottom" width="7%" colspan="2"&gt;&lt;div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt; TEXT-ALIGN: center"&gt;&lt;font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;2009&lt;/font&gt;&lt;/div&gt;&lt;/td&gt;&lt;td style="BORDER-BOTTOM: black 2px solid; TEXT-ALIGN: left" valign="bottom" nowrap="nowrap" width="1%"&gt;&lt;font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;&amp;#160;&lt;/font&gt;&lt;/td&gt;&lt;/tr&gt;&lt;tr&gt;&lt;td valign="bottom" align="left" width="76%"&gt;&lt;div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt" align="left"&gt;&lt;font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;Federal funds sold&lt;/font&gt;&lt;/div&gt;&lt;/td&gt;&lt;td valign="bottom" align="right" width="1%"&gt;&lt;font style="DISPLAY: inline; FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;&amp;#160;&lt;/font&gt;&lt;/td&gt;&lt;td style="TEXT-ALIGN: left" valign="bottom" width="1%"&gt;&lt;font style="DISPLAY: inline; FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;$&lt;/font&gt;&lt;/td&gt;&lt;td style="TEXT-ALIGN: right" valign="bottom" width="6%"&gt;&lt;font style="DISPLAY: inline; FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;19,000&lt;/font&gt;&lt;/td&gt;&lt;td style="TEXT-ALIGN: left" valign="bottom" nowrap="nowrap" width="1%"&gt;&lt;font style="DISPLAY: inline; FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;&amp;#160;&lt;/font&gt;&lt;/td&gt;&lt;td valign="bottom" align="right" width="1%"&gt;&lt;font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;&amp;#160;&lt;/font&gt;&lt;/td&gt;&lt;td style="TEXT-ALIGN: left" valign="bottom" width="1%"&gt;&lt;font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;$&lt;/font&gt;&lt;/td&gt;&lt;td style="TEXT-ALIGN: right" valign="bottom" width="6%"&gt;&lt;font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;11,150&lt;/font&gt;&lt;/td&gt;&lt;td style="TEXT-ALIGN: left" valign="bottom" nowrap="nowrap" width="1%"&gt;&lt;font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;&amp;#160;&lt;/font&gt;&lt;/td&gt;&lt;/tr&gt;&lt;tr&gt;&lt;td style="BORDER-BOTTOM: black 2px solid" valign="bottom" align="left" width="76%"&gt;&lt;div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt" align="left"&gt;&lt;font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;Other short-term interest-bearing investments and deposits&lt;/font&gt;&lt;/div&gt;&lt;/td&gt;&lt;td style="BORDER-BOTTOM: black 2px solid" valign="bottom" align="right" width="1%"&gt;&lt;font style="DISPLAY: inline; FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;&amp;#160;&lt;/font&gt;&lt;/td&gt;&lt;td style="BORDER-BOTTOM: black 2px solid; TEXT-ALIGN: left" valign="bottom" width="1%"&gt;&lt;font style="DISPLAY: inline; FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;&amp;#160;&lt;/font&gt;&lt;/td&gt;&lt;td style="BORDER-BOTTOM: black 2px solid; TEXT-ALIGN: right" valign="bottom" width="6%"&gt;&lt;font style="DISPLAY: inline; FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;426,392&lt;/font&gt;&lt;/td&gt;&lt;td style="BORDER-BOTTOM: black 2px solid; TEXT-ALIGN: left" valign="bottom" nowrap="nowrap" width="1%"&gt;&lt;font style="DISPLAY: inline; FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;&amp;#160;&lt;/font&gt;&lt;/td&gt;&lt;td style="BORDER-BOTTOM: black 2px solid" valign="bottom" align="right" width="1%"&gt;&lt;font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;&amp;#160;&lt;/font&gt;&lt;/td&gt;&lt;td style="BORDER-BOTTOM: black 2px solid; TEXT-ALIGN: left" valign="bottom" width="1%"&gt;&lt;font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;&amp;#160;&lt;/font&gt;&lt;/td&gt;&lt;td style="BORDER-BOTTOM: black 2px solid; TEXT-ALIGN: right" valign="bottom" width="6%"&gt;&lt;font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;201,069&lt;/font&gt;&lt;/td&gt;&lt;td style="BORDER-BOTTOM: black 2px solid; TEXT-ALIGN: left" valign="bottom" nowrap="nowrap" width="1%"&gt;&lt;font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;&amp;#160;&lt;/font&gt;&lt;/td&gt;&lt;/tr&gt;&lt;tr&gt;&lt;td style="BORDER-BOTTOM: black 4px double" valign="bottom" align="left" width="76%"&gt;&lt;div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt" align="left"&gt;&lt;font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;Total&lt;/font&gt;&lt;/div&gt;&lt;/td&gt;&lt;td style="BORDER-BOTTOM: black 4px double" valign="bottom" align="right" width="1%"&gt;&lt;font style="DISPLAY: inline; FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;&amp;#160;&lt;/font&gt;&lt;/td&gt;&lt;td style="BORDER-BOTTOM: black 4px double; TEXT-ALIGN: left" valign="bottom" width="1%"&gt;&lt;font style="DISPLAY: inline; FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;$&lt;/font&gt;&lt;/td&gt;&lt;td style="BORDER-BOTTOM: black 4px double; TEXT-ALIGN: right" valign="bottom" width="6%"&gt;&lt;font style="DISPLAY: inline; FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;445,392&lt;/font&gt;&lt;/td&gt;&lt;td style="BORDER-BOTTOM: black 4px double; TEXT-ALIGN: left" valign="bottom" nowrap="nowrap" width="1%"&gt;&lt;font style="DISPLAY: inline; FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;&amp;#160;&lt;/font&gt;&lt;/td&gt;&lt;td style="BORDER-BOTTOM: black 4px double" valign="bottom" align="right" width="1%"&gt;&lt;font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;&amp;#160;&lt;/font&gt;&lt;/td&gt;&lt;td style="BORDER-BOTTOM: black 4px double; TEXT-ALIGN: left" valign="bottom" width="1%"&gt;&lt;font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;$&lt;/font&gt;&lt;/td&gt;&lt;td style="BORDER-BOTTOM: black 4px double; TEXT-ALIGN: right" valign="bottom" width="6%"&gt;&lt;font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;212,219&lt;/font&gt;&lt;/td&gt;&lt;td style="BORDER-BOTTOM: black 4px double; TEXT-ALIGN: left" valign="bottom" nowrap="nowrap" width="1%"&gt;&lt;font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"&gt;&amp;#160;&lt;/font&gt;&lt;/td&gt;&lt;/tr&gt;&lt;/table&gt;&lt;/div&gt;&lt;div style="DISPLAY: block; TEXT-INDENT: 0pt"&gt;&lt;br /&gt;&lt;/div&gt;&lt;div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 36pt; MARGIN-RIGHT: 0pt" align="left"&gt;&lt;font style="DISPLAY: inline; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman"&gt;Federal funds at December 31, 2010 were sold on an overnight basis.&amp;#160;&amp;#160;Interest-bearing deposits at December 31, 2010 included $412 million with the regional Federal Reserve Bank.&amp;#160;&amp;#160;At December 31, 2010, interest-bearing deposits totaling approximately $12 million were pledged to secure the Bank&amp;#8217;s obligations to certain counterparties under derivative financial instruments and its conditional obligations associated with certain off-balance-sheet financial instruments.&lt;/font&gt;&lt;/div&gt;&lt;br /&gt;</NonNumbericText><NonNumericTextHeader>NOTE 4FEDERAL FUNDS SOLD AND SHORT-TERM INVESTMENTSThe balance of federal funds sold and short-term investments included the following.&amp;#160; 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