Startup IPO’d. Most tax-advantageous way to report?

Hello and thank you for your advice today!

I had joined a startup back in 2015, and early-exercised some shares (no 83b filed). This year, the startup IPO’d, and the shares became real money. The 180-day holding period ended, and the company has opened up transfer of the shares from their custodians into our preferred brokerage accounts. My questions were:

Does this transfer event count as income, or would it trigger AMT? Would long-term gains tax advantages apply here if I were to hold it for over 1 year, or did the early exercise in 2015 already take care of that?

Ultimately, what would be the most tax-advantageous way to go about this transfer? There might be a sell-to-cover option, but I have a feeling that might not be the best. The gross value is less than $100k, if that matters.

Thank you!

posted