59 with sudden wealth from employer stock. How do we unwind a huge concentrated position?

My spouse and I are 59 and recently ended up in a much different financial position than we expected because of employer stock appreciation.

We have a home worth around $2.5M thats paid off, about $1M in 401k, and roughly $300k in cash. The big issue is that we also have around $3.5M in a longtime employer stock and another $3.7M in a stock from a related company. Total net worth is roughly $11M, with about $8.5M outside the house.

A large part of this came from employer stock at a legacy storage company. Over time, corporate changes and restructuring left us with large positions in two related publicly traded companies.

Our spending has historically been pretty modest, around $100k/yr not including healthcare.

We know we’re lucky to be in this spot. But roughly $7.2M is now tied up in two related stocks that have both run up a lot in the past year. It feels great, but also pretty scary at this age.

We mostly want to turn this into a durable retirement plan without making a huge tax mistake or panic-selling.

For people who have dealt with large positions in a small number of stocks, how would you approach this?