Latex tabular text alignment

Three additional possibilities using either tabularx or an itemize list:

documentclass{article} 
usepackage[margin=2.5cm]{geometry}
usepackage{multirow}
usepackage{tabularx}
usepackage{booktabs}
usepackage{graphicx}
usepackage{enumitem}
begin{document}

noindent
begin{tabularx}{textwidth}{@{}l>{raggedrightarraybackslash}p{3.5cm}X@{}}

toprule

& Autor (Jahr) & Definition  
midrule

multirow{16}*{rotatebox{90}{Systemrisikobeitrag}}
& LAWARE (1991) &
"Systemic risk refers to the possibility that financial difficulties at one bank, or possibly a small number of banks, may spill over to many more banks and perhaps the entire financial system. So long as problems can be isolated at a limited number of banks, but confidence maintained in the broader banking and financial system, there is little or no systemic risk.", S. 550.  
addlinespace
& BANK FÜR INTERN. ZAHLUNGS- AUSGLEICH (1994) &
"The risk that the failure of a participant to meet its contractual obligations may in turn cause other participants to default, with the chain reaction leading to broader financial difficulties", S. 177. 
addlinespace
& ROCHET/TIROLE (1996) &
"Systemic risk refers to the propagation of an agent's economic distress to other agents linked to that agent through financial transactions", S. 733.  
addlinespace
& HELLWIG (1998) & 
"[Systemrisiko soll] das Problem bezeichnen, daß (!) aufgrund von wechselseitigen Abhängigkeiten verschiedener Institutionen in einem Finanzsystem die Schwierigkeiten einer Institution die Funktionsfähigkeit des gesamten Systems infrage stellen können", S. 125. 

%noalign{bigskip}
cmidrule{2-3}

multirow{12}*{rotatebox{90}{Systemrisikoempfindlichkeit}}
& DAVIS (1995) & 
",Systemic risk‘ [is] used to describe a disturbance in financial markets which entails unanticipated changes in prices and quantities in credit or asset markets, which lead to a danger of failure of financial firms, and which in turn threatens to spread so as to disrupt the payments mechanism and capacity of the financial system to allocate capital", S. 117. 
addlinespace
& BARTHOLOMEW/ WHALEN (1995) &
"Systemic risk refers to an event having effects on the entire banking, financial, or economic system rather than just one or a few institutions", S. 4. 
addlinespace
& MISHKIN (1995) &
"Systemic risk is the likelihood of a sudden, usually unexpected, event that disrupts information in financial markets, making them unable to effectively channel funds to those parties with the most productive investment opportunities", S. 32. 

%noalign{bigskip}
cmidrule{2-3}

multirow{13}*{rotatebox{90}{Systemkorrelationsrisiko}}
& DAS/UPPAL (2004) & 
"The risk from infrequent events that are highly correlated across a large number of assets", S. 2810. 
addlinespace
& ERGUNGOR/ THOMSON (2005) &
"In a systemic crisis, multiple banks fail simultaneously, and the collective failure impairs enough of the banking system’s capital so that large economic effects are likely to result and the government is required to intervene", S. 2. 
addlinespace
& KRAHNEN (2006) &
"Das systemische Bankenrisiko ergibt sich aus dem gemeinsamen Ausfall mehrerer (juristisch) unabhängiger Finanzinstitute. Das so verstandene systemische Risiko eines Finanzmarktes gibt Auskunft über die Wahrscheinlichkeit, dass aufgrund negativer Entwicklungen mehrere Bankinstitute gleichzeitig in Schwierigkeiten geraten", S. 58. 
addlinespace
& ACHARYA (2009) & 
"We define systemic risk as the joint failure risk arising from the correlation of returns on the asset side of bank balance sheets", S. 225. 

bottomrule

end{tabularx}

clearpage
noindent
begin{tabularx}{textwidth}{@{quad}>{raggedrightarraybackslash}p{3.5cm}X}

toprule

 Autor (Jahr) & Definition  
 
midrule
multicolumn{2}{@{}l}{itshape Systemrisikobeitrag}
midrule

 LAWARE (1991) &
"Systemic risk refers to the possibility that financial difficulties at one bank, or possibly a small number of banks, may spill over to many more banks and perhaps the entire financial system. So long as problems can be isolated at a limited number of banks, but confidence maintained in the broader banking and financial system, there is little or no systemic risk.", S. 550.  
addlinespace
 BANK FÜR INTERN. ZAHLUNGS- AUSGLEICH (1994) &
"The risk that the failure of a participant to meet its contractual obligations may in turn cause other participants to default, with the chain reaction leading to broader financial difficulties", S. 177. 
addlinespace
 ROCHET/TIROLE (1996) &
"Systemic risk refers to the propagation of an agent's economic distress to other agents linked to that agent through financial transactions", S. 733.  
addlinespace
 HELLWIG (1998) & 
"[Systemrisiko soll] das Problem bezeichnen, daß (!) aufgrund von wechselseitigen Abhängigkeiten verschiedener Institutionen in einem Finanzsystem die Schwierigkeiten einer Institution die Funktionsfähigkeit des gesamten Systems infrage stellen können", S. 125. 

midrule
multicolumn{2}{@{}l}{itshape Systemrisikoempfindlichkeit} 
midrule

 DAVIS (1995) & 
",Systemic risk‘ [is] used to describe a disturbance in financial markets which entails unanticipated changes in prices and quantities in credit or asset markets, which lead to a danger of failure of financial firms, and which in turn threatens to spread so as to disrupt the payments mechanism and capacity of the financial system to allocate capital", S. 117. 
addlinespace
 BARTHOLOMEW/ WHALEN (1995) &
"Systemic risk refers to an event having effects on the entire banking, financial, or economic system rather than just one or a few institutions", S. 4. 
addlinespace
 MISHKIN (1995) &
"Systemic risk is the likelihood of a sudden, usually unexpected, event that disrupts information in financial markets, making them unable to effectively channel funds to those parties with the most productive investment opportunities", S. 32. 


midrule
multicolumn{2}{@{}l}{itshape Systemkorrelationsrisiko} 
midrule

 DAS/UPPAL (2004) & 
"The risk from infrequent events that are highly correlated across a large number of assets", S. 2810. 
addlinespace
 ERGUNGOR/ THOMSON (2005) &
"In a systemic crisis, multiple banks fail simultaneously, and the collective failure impairs enough of the banking system’s capital so that large economic effects are likely to result and the government is required to intervene", S. 2. 
addlinespace
 KRAHNEN (2006) &
"Das systemische Bankenrisiko ergibt sich aus dem gemeinsamen Ausfall mehrerer (juristisch) unabhängiger Finanzinstitute. Das so verstandene systemische Risiko eines Finanzmarktes gibt Auskunft über die Wahrscheinlichkeit, dass aufgrund negativer Entwicklungen mehrere Bankinstitute gleichzeitig in Schwierigkeiten geraten", S. 58. 
addlinespace
 ACHARYA (2009) & 
"We define systemic risk as the joint failure risk arising from the correlation of returns on the asset side of bank balance sheets", S. 225. 

bottomrule

end{tabularx}

clearpage


begin{itemize}
  item Systemrisikobeitrag
  begin{itemize}
    item   LAWARE (1991):
"Systemic risk refers to the possibility that financial difficulties at one bank, or possibly a small number of banks, may spill over to many more banks and perhaps the entire financial system. So long as problems can be isolated at a limited number of banks, but confidence maintained in the broader banking and financial system, there is little or no systemic risk.", S. 550. 

item BANK FÜR INTERN. ZAHLUNGS- AUSGLEICH (1994):
"The risk that the failure of a participant to meet its contractual obligations may in turn cause other participants to default, with the chain reaction leading to broader financial difficulties", S. 177. 

item ROCHET/TIROLE (1996): 
"Systemic risk refers to the propagation of an agent's economic distress to other agents linked to that agent through financial transactions", S. 733.
  
item  HELLWIG (1998):  
"[Systemrisiko soll] das Problem bezeichnen, daß (!) aufgrund von wechselseitigen Abhängigkeiten verschiedener Institutionen in einem Finanzsystem die Schwierigkeiten einer Institution die Funktionsfähigkeit des gesamten Systems infrage stellen können", S. 125. 
end{itemize} 

item Systemrisikoempfindlichkeit

begin{itemize}

item DAVIS (1995)  
",Systemic risk‘ [is] used to describe a disturbance in financial markets which entails unanticipated changes in prices and quantities in credit or asset markets, which lead to a danger of failure of financial firms, and which in turn threatens to spread so as to disrupt the payments mechanism and capacity of the financial system to allocate capital", S. 117. 

item BARTHOLOMEW/ WHALEN (1995) 
"Systemic risk refers to an event having effects on the entire banking, financial, or economic system rather than just one or a few institutions", S. 4. 

item MISHKIN (1995) 
"Systemic risk is the likelihood of a sudden, usually unexpected, event that disrupts information in financial markets, making them unable to effectively channel funds to those parties with the most productive investment opportunities", S. 32. 

end{itemize}

item Systemkorrelationsrisiko

begin{itemize}
item  DAS/UPPAL (2004)  
"The risk from infrequent events that are highly correlated across a large number of assets", S. 2810. 

item ERGUNGOR/ THOMSON (2005) 
"In a systemic crisis, multiple banks fail simultaneously, and the collective failure impairs enough of the banking system’s capital so that large economic effects are likely to result and the government is required to intervene", S. 2. 

item KRAHNEN (2006) 
"Das systemische Bankenrisiko ergibt sich aus dem gemeinsamen Ausfall mehrerer (juristisch) unabhängiger Finanzinstitute. Das so verstandene systemische Risiko eines Finanzmarktes gibt Auskunft über die Wahrscheinlichkeit, dass aufgrund negativer Entwicklungen mehrere Bankinstitute gleichzeitig in Schwierigkeiten geraten", S. 58. 

item ACHARYA (2009)  
"We define systemic risk as the joint failure risk arising from the correlation of returns on the asset side of bank balance sheets", S. 225. 

end{itemize}
end{itemize}
end{document}