English to German Bus/Financial Investment / Securities

Es geht um den Markt für Untenehmensanleihen:

Long end USD credits suffered from the move in rates, while the short end of the curve remained somewhat insulated. Spreads continued to grind tighter, activity remaining skewed towards buying and benefiting from ***month-end rebalancing***, as well as rallying equities. Primary market activity kept up a busy start to September, on both the corporate and sovereign side, with Germany issuing its first ever Green bond.


Kann mir jemand sagen, was hier mit "month-end rebalancing" gemeint ist?