▁comm od ities : ▁W TI ▁cru de ▁oil , ▁he ating ▁oil , ▁al umin ium , ▁gold , ▁corn ▁and ▁whe at . ▁The ▁same ▁rolling ▁schedule ▁as ▁the ▁DB L CI . ▁▁ ▁No ▁annual ▁re bal ancing . ▁Instead ▁comm od ity ▁weights ▁are ▁adjust ed ▁according ▁to ▁a ▁pre - defined ▁formula . ▁ ▁It ▁is ▁the ▁only ▁comm od ity ▁index ▁in ▁the ▁market place ▁which ▁poss esses ▁a ▁dynamic ▁rule - based ▁asset ▁allocation ▁mechanism ▁which ▁attempts ▁to ▁under weight ▁" exp ensive ▁comm od ities ▁and ▁over weight ▁" che ap " ▁comm od ities . ▁ ▁Total ▁and ▁excess ▁returns ▁data ▁are ▁available ▁from ▁December ▁ 1 , ▁ 1 9 8 8 . ▁ ▁R ationale ▁and ▁Index ▁Mechan ism ▁ ▁The ▁DB L CI - Me an ▁Re version ▁is ▁the ▁only ▁index ▁which ▁dynamically ▁changes ▁its ▁weights ▁according ▁to ▁whether ▁a ▁comm od ity ▁is ▁considered ▁cheap ▁or ▁expensive . ▁When ▁all ▁the ▁comm od ities ▁are ▁within ▁ 5 % ▁of ▁their ▁five - year ▁aver ages , ▁the ▁weights ▁will ▁automatically ▁revert ▁to ▁the ▁weights ▁of ▁the ▁base ▁index , ▁the ▁DB L CI . ▁The ▁r ationale ▁behind ▁the ▁construction ▁of ▁the ▁D BC LI - MR ▁is ▁to ▁explo it ▁the ▁t endency ▁of ▁comm od ity ▁prices ▁to ▁trade ▁within ▁wide , ▁but , ▁defined ▁ranges ▁because : ▁ ▁As ▁prices ▁of ▁comm od ities ▁rise , ▁new ▁production ▁capacity ▁is ▁brought ▁on ▁line ▁to ▁benefit