The vast majority of viruses and other malware is written for the most-popular PC operating system: Windows. As of 10/28/19 GlobalStats reports that 72.9% of desktop PCs run Windows, followed by 21.1% that run Apple’s OSX.
Best practice is to never log on to your banking website if you run a Windows PC. Instead, build a “Live CD” (or use a USB flash drive for quicker startup) that boots it with a less-popular operating system like Linux. You can then run its browser to surf to your banking website. When you’re done, just eject the Live CD (or flash drive) then restart your PC normally.
Most quality Live CDs are virus-free so you should have no worries. Here’s a good article by Brian Krebs on how to build a Live CD, plus several other useful tips: