A vicious circle (or cycle) is a complex chain of events that reinforces itself through a feedback loop, with detrimental results.
A vicious circle will continue in the direction of its momentum until an external factor intervenes to break the cycle.
The contemporary subprime mortgage crisis is a complex group of vicious circles, both in its genesis and in its manifold outcomes, most notably the late 2000s recession.
Economist Nouriel Roubini discussed vicious circles in the housing and financial markets in interviews with Charlie Rose in September and October 2008.
In 2021, Austrian Chancellor Alexander Schallenberg described the recurring need for lockdowns in the COVID-19 pandemic as a vicious circle that could only be broken by a legally-required vaccination program.