Ka soo qaad dhaleeceynta ay aragtida casriga ah ee faylalka ay ka soo horjeedo xiriirkan https://en.wikipedia.org/wiki/Modern_portfolio_theory, ku rid liiska xabbadda
Context:In kasta oo ay muhiimad aragti ah leedahay, dadka dhaleeceeya MPT waxay su'aal ka keenaan inay tahay qalab maalgashi oo ku habboon, maxaa yeelay qaabkeeda suuqyada maaliyadeed kuma habboona adduunka dhabta ah siyaabo badan  Halista, soo noqoshada, iyo isbarbar dhigga ay adeegsadaan MPT waxay ku saleysan yihiin [qiimaha la filayo] ((https://en.wikipedia.org/wiki/Expected_value), taas oo macnaheedu yahay inay yihiin bayaanno tirakoob oo ku saabsan mustaqbalka (qiimaha la filayo ee soo noqoshada ayaa si cad loogu qeexay isla'egyada kor ku xusan, oo si qarsoodi ah loogu qeexay [isbeddelka] ((https://en.wikipedia.org/wiki/Variance)) iyo [covariance] ((https://en.wikipedia.org/wiki/Covariance)). Tallaabooyinka noocan oo kale ah inta badan ma qabsan karaan astaamaha tirakoobka dhabta ah ee halista iyo soo noqoshada oo inta badan raacaya qaybinta aadka u kala jaban (tusaale ahaan [log-normal distribution] ((https://en.wikipedia.org/wiki/Log-normal_distribution)) waxayna keeni kartaa, marka laga reebo hoos u dhaca [isbeddelka] ((https://en.wikipedia.org/wiki/Volatility_(finance))), sidoo kale kororka soo noqoshada. Ficil ahaan, maalgashadayaashu waa inay ku beddelaan saadaasha ku saleysan cabirka taariikhiga ah ee soo noqoshada hantida iyo isbeddelka qiimayaashan. Inta badan qiimaha la filayo ma tixgeliyaan xaalado cusub oo aan jirin markii xogta taariikhiga ah la soo saaray.  Asal ahaan, maalgashadayaashu waxay ku xayiran yihiin qiyaasta xuduudaha muhiimka ah ee xogta suuqa ee la soo dhaafay sababtoo ah MPT waxay isku dayeysaa inay qaabeyso khatarta marka loo eego suurtagalnimada khasaaraha, laakiin waxba kama sheegayo sababta khasaarahaas u dhici karo. Qiyaasaha khatarta la isticmaalay waa [probabilistic] ((https://en.wikipedia.org/wiki/Probability) dabeecad ahaan, mana aha qaab dhismeed. Tani waa farqi weyn marka la barbar dhigo habab badan oo injineernimada ah oo ku saabsan [maareynta khatarta] (https://en.wikipedia.org/wiki/Risk_management).  Xisaabinta xisaabta ee khatarta ayaa sidoo kale faa'iido u leh oo keliya heerka ay ka tarjumeyso welwelka dhabta ah ee maalgashadayaasha. Gaar ahaan, [kala duwanaanshaha] (https://en.wikipedia.org/wiki/Variance) waa qiyaas isbarbar dhiga oo tirinaya soo noqoshada aan caadiga ahayn ee sare sida khatarta ah sida soo noqoshada aan caadiga ahayn ee hooseysa. Dhacdada nafsiga ah ee [Loss aversion] ((https://en.wikipedia.org/wiki/Loss_aversion) waa fikradda ah in maalgashadayaashu ay ka walaacsan yihiin khasaaraha marka loo eego faa'iidooyinka, taasoo la micno ah in fikraddeena dareenka ah ee khatarta ay asal ahaan u tahay mid aan caadi ahayn. Waxaa jira cabbirro kale oo badan oo khatar ah (sida [Coherent_risk_measure] ((https://en.wikipedia.org/wiki/Coherent_risk_measure)) oo laga yaabo inay si fiican u muujiyaan doorbidyada dhabta ah ee maalgashadayaasha.  Aragtida casriga ah ee faylalka ayaa sidoo kale lagu dhaleeceeyay maxaa yeelay waxay u maleyneysaa in soo noqoshada ay raacdo [qaybinta Gaussian] (https://en.wikipedia.org/wiki/Normal_distribution). Horraantii 1960-yadii, [Benoit Mandelbrot] iyo [Eugene Fama] waxay muujiyeen ku filnaan la'aanta aragtidan waxayna soo jeediyeen in la isticmaalo [qaybinta xasilloon] guud ahaan. [Stefan Mittnik] iyo [Slovetzar Rachev] waxay soo bandhigeen istiraatiijiyad ku saabsan soo saarista faylalka ugu fiican goobaha noocan oo kale ah.  Maalgashadayaasha ka soo horjeeda iyo maalgashadayaasha qiimaha leh sida caadiga ah kuma raacsana aragtida casriga ah ee faylalka. Mid ka mid ah diidmada ayaa ah in MPT ay ku tiirsan tahay [shuruudaha suuqa-hufnaanta] wuxuu isticmaalaa isbedelka sicirka saamiyada si uu u bedelo khatarta. Wuxuu aaminsanaa kala duwanaanshaha fikradda ah, laakiin sidoo kale wuxuu dareemay aasaaska aragtida ah ee MPT inay su'aal ka taagan tahay, wuxuuna ku soo gabagabeeyay (sida uu ku tilmaamay qoraaga taariikh nololeedkiisa): "fikradda ah in dhismaha faylalka ku saleysan xogta tirakoobka ee aan la isku halleyn karin oo aan khuseyn, sida isbeddelka taariikhiga ah, ayaa lagu xukumay fashil.
- Halista, soo celinta, iyo isdhexgalka tallaabooyinka loo isticmaalo by aragtida faylalka casriga ah (MPT) waxay ku salaysan yihiin qiimaha la filayo, qiimaha la filayo noocan oo kale ah ku guuldareysato in ay tixgeliyaan xaaladaha cusub oo aan jirin markii xogta taariikhiga ah la soo saaray - Cabbirka khatarta ee loo adeegsado MPT waa mid macquul ah sababtoo ah moodooyinka MPT waxay khatar ku yihiin suurtagalnimada khasaaraha ee ku saleysan xogta suuqa ee la soo dhaafay oo aan ahayn sababta khasaaraha uu u dhaco. - MPT waxay isku daydaa inay yareyso khatarta iyadoo loo marayo kala duwanaansho. Si kastaba ha noqotee, cabirkani ma muujinayo walaacyada dhabta ah ee maalgashadayaasha. Kala duwanaanshuhu waa simetrical, markaa waxay ku cadaabeysaa faa'iidada badan iyo khasaaraha badan. Si kastaba ha noqotee, maalgashadayaashu waxay aad uga taxadaraan khasaaraha in ka badan faa'iidada, sidaa darteed aragtida khatartu waa mid aan caadi ahayn. Qaddarka khatarta ee isku xiran waa inuu noqdaa mid si fiican u muujinaya doorbidka maalgashadayaasha - MPT waxay u maleyneysaa in soo noqoshadu ay raacayso qeybinta Gaussian. Si kastaba ha ahaatee, aqoonyahanno badan ayaa soo jeedinaya in soo noqoshada ay raaci karto qaybinta kale sida qaybinta xasilloon - MPT waxay ku tiirsan tahay mala-awaalka suuqa waxtarka leh waxayna u maleyneysaa in isbedelka qiimaha saamiyada ay tahay cabir khatar ah. Si kastaba ha noqotee, dhismaha sanduuq ku saleysan isbeddelka taariikhiga ah waa aasaas su'aal ah oo uu dhaleeceeyay Sir John Templeton