In order to save money, the bank's equity and derivatives division, BNP Paribas Arbitrage, is exploiting 6,000 computing hours out of 700 PCs that would have otherwise stood idle.
The division is deploying Platform Computing's Symphony package to free up the processing power of the abandoned machines.
BNP IT manager Denis Esnault told silicon.com: "It's an economical reason - we have a lot of PCs which are doing nothing during the night. We have this free resource which we can use.
"The price of the [grid software] license is quite cheap compared to the cost of buying [more] computers. The price is something very important for us - if it's not cheaper there's no economic value to doing it with the PCs."
The bank plans to extend the grid to operations in Hong Kong, New York and Tokyo. Platform says 2,000 desktops can be incorporated in the grid.
On average, financial services organizations have 20,000 desktop PCs operating at just ten per cent capacity, according to Platform Computing.