Private markets take 3-5% of a deal, require a 3-way contract, and thus won't do anything below $100K. They are indeed fragmented, disorganized and inefficient. If Carta can solve that, great.
In my experience, spreads are closer to 1 to 5%. The upper end of that spectrum dominates in the trading employees' shares, however, so there is a fair point here.
That said, CartaX isn't comparable to the open secondary markets. The latter are continuous. CartaX is periodic.
The better comparison is Nasdaq Private Markets, who offer a similar tender offer platform. Last time I checked, they charge a fixed fee plus something like $500 per trade. Compared with this, the 2% CartaX charge is only competitive for <$25,000 transactions.
> won't do anything below $100K
This is generally correct for open market trades. (Though folks like EquityZen are pushing the envelope on minimum transaction sizes.) It is not true for tenders.
CartaX looks like a pricier Nasdaq Private Markets. Perhaps that premium--and the ongoing disclosure requirements and lock-in--is worth paying for some issuers.