They have been plying their trade for years - in this case accumulating surplus from oil sales or exports and reinvesting the money overseas - without anyone paying them much attention.
The managers feel no need to explain themselves to anyone other than their investors and business associates, because they feel they are doing nothing out of the ordinary, and besides it is their money they are dealing with.
Suddenly, however, something happens that tips them over into the public domain. For the first time a wider audience of politicians, the public and the media become aware of their existence and realise that here are organisations with immense wealth and power about which they know nothing.
This sparks a reaction of fear and distrust. Fear because these funds are so big they seem able to do and buy what they want. And distrust because nothing is known about them and if there is nothing to hide, why are they being so secretive?
The world changed for sovereign funds when they started injecting funds into the US banking system. Thank goodness they did because the Americans need the money - but xenophobia and protectionism are never far below the surface in the US.
The gratitude that politicians, bankers and others feel for the bailout is already tinged with resentment that the US got itself into such a mess in the first place. There is also a fear that this comes with political strings, even if these are not immediately obvious.
But unlike the private equity industry, which fell into a hopeless political row from which it emerged the loser, the sovereign wealth funds see what is happening, and want to do something about it.
Last week it was announced that Abu Dhabi Investment Authority, the world's largest single fund with some $800m of investments, had hired Burson Marsteller. Presumably with the brief to reassure Congress and the public that Abu Dhabi is a passive investor with no ulterior motive. How long before the other funds feel the need to do likewise?,
Anthony Hilton is City commentator on London's Evening Standard