They probably have significantly better raw data sets than even their competitors like AQR or Two Sigma. Satellite data on parking lots. Credit card swipe statistics. Parsed and structures full financials. Supplier consumer relationships. Analyst data. Short interest data. Options activity. Fund holdings. ... Everything you can possibly think of. All integrated into a single streamline analytical and modeling technological infrastructure.

So yes to us little people it is insider trading. But I’m 99% sure it is real alpha at the core.

Not necessarily, they could be money laundering instead.

Continuing the speculation, they could be just "picking" the stocks after the fact when the returns are already known, iff there is no external record of their positions and transactions

There is an external record, 13F filings. Every quarter funds above a certain AUM have to disclose to the public their top long equity holdings. I’ve personally analyzed these holdings at my old quant job, they definately trade.

SAC Capital says hi