second wave down since gfc about to start, page-9

its come out recently that american pension funds are having trouble meeting their promised obligations. that is their promised returns. i dont know what exactly happened but it goes something like this. the american states or the american government itself, im not sure which, promised their pensioners a certain return on their money tied up in these funds. not sure if it was a government guaranteed return. this is a vague idea of what occured i think, im not an economist.
but i think what has occured is these funds have invested heavily in the american stock market to try and make up for their recent shortfalls in returns. they have taken on more than normal risk to meet their promised returns. these funds have trillions of dollars under management.
the above may be a bit simple but it doesnt look good. what if these funds get caught out.