Why concentration is fragile

When value piles into one card, set, or player, a single bad event — an injury, a scandal, a market shift, or damage to that one slab — can wipe out a large share of the collection at once. Diversification softens that blow.

How to think about it

Look at what percentage of total value sits in your single largest card, and in your top player or set. The higher those shares, the more your fortunes ride on one outcome you do not control.

Measure it, then manage it

Slabline scores concentration as one of its five factors (25% of the Slabline Score), so you can see your exposure at a glance and decide whether to diversify, trim, or simply insure that one card especially well.