Giant asset managers are becoming the titans of Wall Street and increasing their control over the US financial system. 

Huge investment firms now control twice as many assets as once-dominant US banks - managing sums which rival the economies of large countries across the world, it has been reported.

Assets held by Boston-based fund manager State Street in 2023 totaled $4.13 trillion, according to The Wall Street Journal. 

This was more than the gross domestic product (GDP) of Germany, which was $4.08 trillion in 2022. 

Investment management company Blackstone, which is based in New York City, held $1.04 trillion in assets last year - higher than the $1.01 trillion GDP of the Netherlands in 2022.

Funds manage assets for pension plans, wealthy individuals and companies.

These fund-management companies are offering new types of products in order to capture market share, The Wall Street Journal reported. 

The biggest are turning into so-called 'financial supermarkets', it said, offering products not just for the wealthy and for big institutions, but also for middle-class investors. 

Asset managers are also replacing banks as lenders to US companies and consumers, it reported, and forming deals with insurance companies to turbocharge growth. 

Four of the biggest public-fund managers - BlackRock, Fidelity, State Street and Vanguard - control about $26 trillion, which is equivalent to the entire annual US economic output. 

This growth started out of the 2008 financial crisis.