If M.2 share bandwidth with my SATA, does that make it slow as SATA?

I'm new to this whole PC building thing and while shopping for a motherboard, I've found that the M.2 slot, if used, will disable a SATA port (or 2). After further research, I've found that it might be because they share the same bandwidth.

Does that mean that the M.2 port will be limited to the same 6GB/s speed limit of SATA ports? Can anyone clarify my mind about this?

Thanks in advance.

I've found that the M.2 slot, if used, will disable a SATA port (or 2).

Wikipedia suggests the following:

Computer bus interfaces provided through the M.2 connector are PCI Express 3.0 (up to four lanes), Serial ATA 3.0, and USB 3.0 (a single logical port for each of the latter two).

If your M.2 connector disables a SATA 3 port it means the maximum speeds it can reach is that of what SATA 3 can provide. This means if a identical SSD product were to exist in both a 3.5"/2.5" form factor and a M.2 form factor they would perform identically.

Does that mean that the M.2 port will be limited to the same 6GB/s speed limit of SATA ports?

Yes, it means exactly that.

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