I am strongly against a secondary market for neurons. No one would be able to anticipate how an actor with hostile takeover intentions could social engineer people into selling their neurons or how the holder would dump the neuron price on such a market in a stressed market scenario. Preferably, introduce an unwinding mechanism where the neuron holder pays a non-linear (based on time to maturity, dissolve time, etc) termination fee in ICP (a % of the ICP locked in the neuron) that goes straight to Dfinity or distributed pro rata to all neuron holders as locked ICP in their configured neurons. Dissolve/unwind the neuron and the remaining ICP after termination fee goes back to the holder which then can be sold on the market.