What are the legal complications such transfer may have on my H1B visa?

I have an valid H1B visa from company A. I never been to US, but now I have another offer from company B who is willing to transfer my visa.Did company A own rights to cancel H1B? What are the legal complications such transfer may have on my H1B visa? If this transfer is possible, how long it would take to complete the Process.

Thanks

Yes employer A has the right to cancel your visa, but they do not need to know before you already have a new visa from employer B based on the current approved petition.There are no legal complications with such transfers. The process would take 3-5 months in regular processing and 15 days in premium processing.