<?xml version="1.0" encoding="utf-8"?>
<ns1:informationTable xmlns:ns1="http://www.sec.gov/edgar/document/thirteenf/informationtable">
  <ns1:infoTable>
    <ns1:nameOfIssuer>ISHARES INC</ns1:nameOfIssuer>
    <ns1:titleOfClass>CORE MSCI EMKT</ns1:titleOfClass>
    <ns1:cusip>46434G103</ns1:cusip>
    <ns1:figi>BBG003HC3DG9</ns1:figi>
    <ns1:value>114168125</ns1:value>
    <ns1:shrsOrPrnAmt>
      <ns1:sshPrnamt>1636819</ns1:sshPrnamt>
      <ns1:sshPrnamtType>SH</ns1:sshPrnamtType>
    </ns1:shrsOrPrnAmt>
    <ns1:investmentDiscretion>SOLE</ns1:investmentDiscretion>
    <ns1:otherManager>1</ns1:otherManager>
    <ns1:votingAuthority>
      <ns1:Sole>1636819</ns1:Sole>
      <ns1:Shared>0</ns1:Shared>
      <ns1:None>0</ns1:None>
    </ns1:votingAuthority>
  </ns1:infoTable>
  <ns1:infoTable>
    <ns1:nameOfIssuer>SCHWAB STRATEGIC TR</ns1:nameOfIssuer>
    <ns1:titleOfClass>US TIPS ETF</ns1:titleOfClass>
    <ns1:cusip>808524870</ns1:cusip>
    <ns1:figi>BBG001T9F777</ns1:figi>
    <ns1:value>237037862</ns1:value>
    <ns1:shrsOrPrnAmt>
      <ns1:sshPrnamt>8907849</ns1:sshPrnamt>
      <ns1:sshPrnamtType>SH</ns1:sshPrnamtType>
    </ns1:shrsOrPrnAmt>
    <ns1:investmentDiscretion>SOLE</ns1:investmentDiscretion>
    <ns1:otherManager>1</ns1:otherManager>
    <ns1:votingAuthority>
      <ns1:Sole>8907849</ns1:Sole>
      <ns1:Shared>0</ns1:Shared>
      <ns1:None>0</ns1:None>
    </ns1:votingAuthority>
  </ns1:infoTable>
  <ns1:infoTable>
    <ns1:nameOfIssuer>VANGUARD BD INDEX FDS</ns1:nameOfIssuer>
    <ns1:titleOfClass>INTERMED TERM</ns1:titleOfClass>
    <ns1:cusip>921937819</ns1:cusip>
    <ns1:figi>BBG001ST39R1</ns1:figi>
    <ns1:value>168707222</ns1:value>
    <ns1:shrsOrPrnAmt>
      <ns1:sshPrnamt>2185893</ns1:sshPrnamt>
      <ns1:sshPrnamtType>SH</ns1:sshPrnamtType>
    </ns1:shrsOrPrnAmt>
    <ns1:investmentDiscretion>SOLE</ns1:investmentDiscretion>
    <ns1:otherManager>1</ns1:otherManager>
    <ns1:votingAuthority>
      <ns1:Sole>2185893</ns1:Sole>
      <ns1:Shared>0</ns1:Shared>
      <ns1:None>0</ns1:None>
    </ns1:votingAuthority>
  </ns1:infoTable>
  <ns1:infoTable>
    <ns1:nameOfIssuer>VANGUARD BD INDEX FDS</ns1:nameOfIssuer>
    <ns1:titleOfClass>LONG TERM BOND</ns1:titleOfClass>
    <ns1:cusip>921937793</ns1:cusip>
    <ns1:figi>BBG001ST39S0</ns1:figi>
    <ns1:value>180698403</ns1:value>
    <ns1:shrsOrPrnAmt>
      <ns1:sshPrnamt>2627194</ns1:sshPrnamt>
      <ns1:sshPrnamtType>SH</ns1:sshPrnamtType>
    </ns1:shrsOrPrnAmt>
    <ns1:investmentDiscretion>SOLE</ns1:investmentDiscretion>
    <ns1:otherManager>1</ns1:otherManager>
    <ns1:votingAuthority>
      <ns1:Sole>2627194</ns1:Sole>
      <ns1:Shared>0</ns1:Shared>
      <ns1:None>0</ns1:None>
    </ns1:votingAuthority>
  </ns1:infoTable>
  <ns1:infoTable>
    <ns1:nameOfIssuer>VANGUARD BD INDEX FDS</ns1:nameOfIssuer>
    <ns1:titleOfClass>SHORT TRM BOND</ns1:titleOfClass>
    <ns1:cusip>921937827</ns1:cusip>
    <ns1:figi>BBG001ST39Q2</ns1:figi>
    <ns1:value>306115228</ns1:value>
    <ns1:shrsOrPrnAmt>
      <ns1:sshPrnamt>3904033</ns1:sshPrnamt>
      <ns1:sshPrnamtType>SH</ns1:sshPrnamtType>
    </ns1:shrsOrPrnAmt>
    <ns1:investmentDiscretion>SOLE</ns1:investmentDiscretion>
    <ns1:otherManager>1</ns1:otherManager>
    <ns1:votingAuthority>
      <ns1:Sole>3904033</ns1:Sole>
      <ns1:Shared>0</ns1:Shared>
      <ns1:None>0</ns1:None>
    </ns1:votingAuthority>
  </ns1:infoTable>
  <ns1:infoTable>
    <ns1:nameOfIssuer>VANGUARD CHARLOTTE FDS</ns1:nameOfIssuer>
    <ns1:titleOfClass>TOTAL INT BD ETF</ns1:titleOfClass>
    <ns1:cusip>92203J407</ns1:cusip>
    <ns1:figi>BBG004N1LGK2</ns1:figi>
    <ns1:value>226235929</ns1:value>
    <ns1:shrsOrPrnAmt>
      <ns1:sshPrnamt>4708344</ns1:sshPrnamt>
      <ns1:sshPrnamtType>SH</ns1:sshPrnamtType>
    </ns1:shrsOrPrnAmt>
    <ns1:investmentDiscretion>SOLE</ns1:investmentDiscretion>
    <ns1:otherManager>1</ns1:otherManager>
    <ns1:votingAuthority>
      <ns1:Sole>4708344</ns1:Sole>
      <ns1:Shared>0</ns1:Shared>
      <ns1:None>0</ns1:None>
    </ns1:votingAuthority>
  </ns1:infoTable>
  <ns1:infoTable>
    <ns1:nameOfIssuer>VANGUARD INDEX FDS</ns1:nameOfIssuer>
    <ns1:titleOfClass>EXTEND MKT ETF</ns1:titleOfClass>
    <ns1:cusip>922908652</ns1:cusip>
    <ns1:figi>BBG001SK3J43</ns1:figi>
    <ns1:value>34741098</ns1:value>
    <ns1:shrsOrPrnAmt>
      <ns1:sshPrnamt>168810</ns1:sshPrnamt>
      <ns1:sshPrnamtType>SH</ns1:sshPrnamtType>
    </ns1:shrsOrPrnAmt>
    <ns1:investmentDiscretion>SOLE</ns1:investmentDiscretion>
    <ns1:otherManager>1</ns1:otherManager>
    <ns1:votingAuthority>
      <ns1:Sole>168810</ns1:Sole>
      <ns1:Shared>0</ns1:Shared>
      <ns1:None>0</ns1:None>
    </ns1:votingAuthority>
  </ns1:infoTable>
  <ns1:infoTable>
    <ns1:nameOfIssuer>VANGUARD INDEX FDS</ns1:nameOfIssuer>
    <ns1:titleOfClass>GROWTH ETF</ns1:titleOfClass>
    <ns1:cusip>922908736</ns1:cusip>
    <ns1:figi>BBG001SHTTS4</ns1:figi>
    <ns1:value>314075160</ns1:value>
    <ns1:shrsOrPrnAmt>
      <ns1:sshPrnamt>719053</ns1:sshPrnamt>
      <ns1:sshPrnamtType>SH</ns1:sshPrnamtType>
    </ns1:shrsOrPrnAmt>
    <ns1:investmentDiscretion>SOLE</ns1:investmentDiscretion>
    <ns1:otherManager>1</ns1:otherManager>
    <ns1:votingAuthority>
      <ns1:Sole>719053</ns1:Sole>
      <ns1:Shared>0</ns1:Shared>
      <ns1:None>0</ns1:None>
    </ns1:votingAuthority>
  </ns1:infoTable>
  <ns1:infoTable>
    <ns1:nameOfIssuer>VANGUARD INDEX FDS</ns1:nameOfIssuer>
    <ns1:titleOfClass>S&amp;P 500 ETF SHS</ns1:titleOfClass>
    <ns1:cusip>922908363</ns1:cusip>
    <ns1:figi>BBG001TC6MC1</ns1:figi>
    <ns1:value>230588570</ns1:value>
    <ns1:shrsOrPrnAmt>
      <ns1:sshPrnamt>385890</ns1:sshPrnamt>
      <ns1:sshPrnamtType>SH</ns1:sshPrnamtType>
    </ns1:shrsOrPrnAmt>
    <ns1:investmentDiscretion>SOLE</ns1:investmentDiscretion>
    <ns1:otherManager>1</ns1:otherManager>
    <ns1:votingAuthority>
      <ns1:Sole>385890</ns1:Sole>
      <ns1:Shared>0</ns1:Shared>
      <ns1:None>0</ns1:None>
    </ns1:votingAuthority>
  </ns1:infoTable>
  <ns1:infoTable>
    <ns1:nameOfIssuer>VANGUARD INDEX FDS</ns1:nameOfIssuer>
    <ns1:titleOfClass>SMALL CP ETF</ns1:titleOfClass>
    <ns1:cusip>922908751</ns1:cusip>
    <ns1:figi>BBG001SHTTV0</ns1:figi>
    <ns1:value>74468571</ns1:value>
    <ns1:shrsOrPrnAmt>
      <ns1:sshPrnamt>284318</ns1:sshPrnamt>
      <ns1:sshPrnamtType>SH</ns1:sshPrnamtType>
    </ns1:shrsOrPrnAmt>
    <ns1:investmentDiscretion>SOLE</ns1:investmentDiscretion>
    <ns1:otherManager>1</ns1:otherManager>
    <ns1:votingAuthority>
      <ns1:Sole>284318</ns1:Sole>
      <ns1:Shared>0</ns1:Shared>
      <ns1:None>0</ns1:None>
    </ns1:votingAuthority>
  </ns1:infoTable>
  <ns1:infoTable>
    <ns1:nameOfIssuer>VANGUARD INDEX FDS</ns1:nameOfIssuer>
    <ns1:titleOfClass>TOTAL STK MKT</ns1:titleOfClass>
    <ns1:cusip>922908769</ns1:cusip>
    <ns1:figi>BBG001SHTB03</ns1:figi>
    <ns1:value>265181546</ns1:value>
    <ns1:shrsOrPrnAmt>
      <ns1:sshPrnamt>826600</ns1:sshPrnamt>
      <ns1:sshPrnamtType>SH</ns1:sshPrnamtType>
    </ns1:shrsOrPrnAmt>
    <ns1:investmentDiscretion>SOLE</ns1:investmentDiscretion>
    <ns1:otherManager>1</ns1:otherManager>
    <ns1:votingAuthority>
      <ns1:Sole>826600</ns1:Sole>
      <ns1:Shared>0</ns1:Shared>
      <ns1:None>0</ns1:None>
    </ns1:votingAuthority>
  </ns1:infoTable>
  <ns1:infoTable>
    <ns1:nameOfIssuer>VANGUARD INDEX FDS</ns1:nameOfIssuer>
    <ns1:titleOfClass>VALUE ETF</ns1:titleOfClass>
    <ns1:cusip>922908744</ns1:cusip>
    <ns1:figi>BBG001SHVR78</ns1:figi>
    <ns1:value>274536578</ns1:value>
    <ns1:shrsOrPrnAmt>
      <ns1:sshPrnamt>1399269</ns1:sshPrnamt>
      <ns1:sshPrnamtType>SH</ns1:sshPrnamtType>
    </ns1:shrsOrPrnAmt>
    <ns1:investmentDiscretion>SOLE</ns1:investmentDiscretion>
    <ns1:otherManager>1</ns1:otherManager>
    <ns1:votingAuthority>
      <ns1:Sole>1399269</ns1:Sole>
      <ns1:Shared>0</ns1:Shared>
      <ns1:None>0</ns1:None>
    </ns1:votingAuthority>
  </ns1:infoTable>
  <ns1:infoTable>
    <ns1:nameOfIssuer>VANGUARD INTL EQUITY INDEX F</ns1:nameOfIssuer>
    <ns1:titleOfClass>ALLWRLD EX US</ns1:titleOfClass>
    <ns1:cusip>922042775</ns1:cusip>
    <ns1:figi>BBG001SP7T00</ns1:figi>
    <ns1:value>249009370</ns1:value>
    <ns1:shrsOrPrnAmt>
      <ns1:sshPrnamt>3315704</ns1:sshPrnamt>
      <ns1:sshPrnamtType>SH</ns1:sshPrnamtType>
    </ns1:shrsOrPrnAmt>
    <ns1:investmentDiscretion>SOLE</ns1:investmentDiscretion>
    <ns1:otherManager>1</ns1:otherManager>
    <ns1:votingAuthority>
      <ns1:Sole>3315704</ns1:Sole>
      <ns1:Shared>0</ns1:Shared>
      <ns1:None>0</ns1:None>
    </ns1:votingAuthority>
  </ns1:infoTable>
  <ns1:infoTable>
    <ns1:nameOfIssuer>VANGUARD INTL EQUITY INDEX F</ns1:nameOfIssuer>
    <ns1:titleOfClass>FTSE EUROPE ETF</ns1:titleOfClass>
    <ns1:cusip>922042874</ns1:cusip>
    <ns1:figi>BBG001SHTV18</ns1:figi>
    <ns1:value>109958240</ns1:value>
    <ns1:shrsOrPrnAmt>
      <ns1:sshPrnamt>1333959</ns1:sshPrnamt>
      <ns1:sshPrnamtType>SH</ns1:sshPrnamtType>
    </ns1:shrsOrPrnAmt>
    <ns1:investmentDiscretion>SOLE</ns1:investmentDiscretion>
    <ns1:otherManager>1</ns1:otherManager>
    <ns1:votingAuthority>
      <ns1:Sole>1333959</ns1:Sole>
      <ns1:Shared>0</ns1:Shared>
      <ns1:None>0</ns1:None>
    </ns1:votingAuthority>
  </ns1:infoTable>
  <ns1:infoTable>
    <ns1:nameOfIssuer>VANGUARD INTL EQUITY INDEX F</ns1:nameOfIssuer>
    <ns1:titleOfClass>FTSE PACIFIC ETF</ns1:titleOfClass>
    <ns1:cusip>922042866</ns1:cusip>
    <ns1:figi>BBG001SHTV36</ns1:figi>
    <ns1:value>75627676</ns1:value>
    <ns1:shrsOrPrnAmt>
      <ns1:sshPrnamt>773843</ns1:sshPrnamt>
      <ns1:sshPrnamtType>SH</ns1:sshPrnamtType>
    </ns1:shrsOrPrnAmt>
    <ns1:investmentDiscretion>SOLE</ns1:investmentDiscretion>
    <ns1:otherManager>1</ns1:otherManager>
    <ns1:votingAuthority>
      <ns1:Sole>773843</ns1:Sole>
      <ns1:Shared>0</ns1:Shared>
      <ns1:None>0</ns1:None>
    </ns1:votingAuthority>
  </ns1:infoTable>
  <ns1:infoTable>
    <ns1:nameOfIssuer>VANGUARD SCOTTSDALE FDS</ns1:nameOfIssuer>
    <ns1:titleOfClass>MTG-BKD SECS ETF</ns1:titleOfClass>
    <ns1:cusip>92206C771</ns1:cusip>
    <ns1:figi>BBG001T62MF5</ns1:figi>
    <ns1:value>178002380</ns1:value>
    <ns1:shrsOrPrnAmt>
      <ns1:sshPrnamt>3791318</ns1:sshPrnamt>
      <ns1:sshPrnamtType>SH</ns1:sshPrnamtType>
    </ns1:shrsOrPrnAmt>
    <ns1:investmentDiscretion>SOLE</ns1:investmentDiscretion>
    <ns1:otherManager>1</ns1:otherManager>
    <ns1:votingAuthority>
      <ns1:Sole>3791318</ns1:Sole>
      <ns1:Shared>0</ns1:Shared>
      <ns1:None>0</ns1:None>
    </ns1:votingAuthority>
  </ns1:infoTable>
  <ns1:infoTable>
    <ns1:nameOfIssuer>VANGUARD SCOTTSDALE FDS</ns1:nameOfIssuer>
    <ns1:titleOfClass>VNG RUS3000IDX</ns1:titleOfClass>
    <ns1:cusip>92206C599</ns1:cusip>
    <ns1:figi>BBG001TCHH58</ns1:figi>
    <ns1:value>133043847</ns1:value>
    <ns1:shrsOrPrnAmt>
      <ns1:sshPrnamt>462641</ns1:sshPrnamt>
      <ns1:sshPrnamtType>SH</ns1:sshPrnamtType>
    </ns1:shrsOrPrnAmt>
    <ns1:investmentDiscretion>SOLE</ns1:investmentDiscretion>
    <ns1:otherManager>1</ns1:otherManager>
    <ns1:votingAuthority>
      <ns1:Sole>462641</ns1:Sole>
      <ns1:Shared>0</ns1:Shared>
      <ns1:None>0</ns1:None>
    </ns1:votingAuthority>
  </ns1:infoTable>
  <ns1:infoTable>
    <ns1:nameOfIssuer>VANGUARD STAR FDS</ns1:nameOfIssuer>
    <ns1:titleOfClass>VG TL INTL STK F</ns1:titleOfClass>
    <ns1:cusip>921909768</ns1:cusip>
    <ns1:figi>BBG001TJR1D8</ns1:figi>
    <ns1:value>111736939</ns1:value>
    <ns1:shrsOrPrnAmt>
      <ns1:sshPrnamt>1449059</ns1:sshPrnamt>
      <ns1:sshPrnamtType>SH</ns1:sshPrnamtType>
    </ns1:shrsOrPrnAmt>
    <ns1:investmentDiscretion>SOLE</ns1:investmentDiscretion>
    <ns1:otherManager>1</ns1:otherManager>
    <ns1:votingAuthority>
      <ns1:Sole>1449059</ns1:Sole>
      <ns1:Shared>0</ns1:Shared>
      <ns1:None>0</ns1:None>
    </ns1:votingAuthority>
  </ns1:infoTable>
  <ns1:infoTable>
    <ns1:nameOfIssuer>VANGUARD TAX-MANAGED FDS</ns1:nameOfIssuer>
    <ns1:titleOfClass>VAN FTSE DEV MKT</ns1:titleOfClass>
    <ns1:cusip>921943858</ns1:cusip>
    <ns1:figi>BBG001SSPWL4</ns1:figi>
    <ns1:value>170043201</ns1:value>
    <ns1:shrsOrPrnAmt>
      <ns1:sshPrnamt>2653608</ns1:sshPrnamt>
      <ns1:sshPrnamtType>SH</ns1:sshPrnamtType>
    </ns1:shrsOrPrnAmt>
    <ns1:investmentDiscretion>SOLE</ns1:investmentDiscretion>
    <ns1:otherManager>1</ns1:otherManager>
    <ns1:votingAuthority>
      <ns1:Sole>2653608</ns1:Sole>
      <ns1:Shared>0</ns1:Shared>
      <ns1:None>0</ns1:None>
    </ns1:votingAuthority>
  </ns1:infoTable>
</ns1:informationTable>
