NEW YORK, Oct 15 (Reuters) - Big U.S. banks" wealth management businesses put in another stellar performance in the third quarter, buoyed by record levels of new money flowing into accounts and surging demand from clients to borrow against their investment portfolios. Morgan Stanley Inc (MS.N), JPMorgan Chase & Co (JPM.N), Bank of America Corp(BAC.N)and Goldman Sachs Group Inc.(GS.N) each reported double-digit growth in wealth management loan balances and revenues this week. While the COVID-19 pandemic devastated large chunks of the economy and put millions out of work, extraordinary government measures aimed at mitigating the economic blow have also boosted the fortunes of the wealthy by pushing down interest rates and driving a massive stock market rally. Global financial wealth soared to a record high of $250 trillion in 2020, according to a June report by Boston Consulting Group. That has increased demand for money managers, increased the value of assets managed by these brokerages, and made it more appealing for customers to borrow. "At the high net worth end of the spectrum, lending products have been very healthy and you"re seeing that at firms like Morgan Stanley where wealth management loan balances are up over 30% year over year," said Devin Ryan, an analyst at JMP Securities. Morgan Stanley"s wealth management business reported revenues of $5.935 billion, up 28% from last year. Wealth management loan balances reached $121 billion, up 33% year-on-year, mostly from clients taking out mortgages and borrowing against their investments. A booming area of lending for wealth management brokerages, so-called securities based loans or lines of credit, allow clients to borrow up to a certain percent of the value of their investment accounts to spend on anything except more securities. As those investment accounts have grown in value, so have loans. Bank of America"s Merrill Lynch Wealth Management reported record revenues of $4.5 billion, up 19% over last year, while loan balances grew 10% to top $133 billion. At JPMorgan"s asset and wealth management business, revenues 21% to $4.3 billion, while average loans rose 20% from last year. Both Bank of America and JPMorgan said the primary driver of loan growth was securities based loans, followed by mortgages and custom loans. Morgan Stanley, which gets around half of its revenues from wealth management, said net new assets rose by 89% to $135 billion in the third quarter from the prior quarter, helped in part by the acquisition of a group of retirement advisers that brought $43 billion in fee-based assets to the bank. read more Bank of America reported that, over the past year, it has brought on more than $112 billion in net new assets across its global wealth management business. Merrill Lynch also added 4,200 net new households, the bank said. Goldman Sachs, which has a smaller wealth management unit catering to the extremely rich, said wealth management net revenues jumped 40% from last year to $1.64 billion, while loan balances were also up 40% to reach $42 billion. JPMorgan does not break out net new assets for its asset and wealth management business.