Quantative trading starts with a hypothesis. Our fundamental opinion is that the central banks, having lowered rate to the zero bound, will destroy the classical stock/bond portfolio in time.
When bonds return negative yield and central banks print money to buy assets, gold seems like a lot more attractive asset than low yielding fiat bonds in bear markets.
Our models predict the probability of bull markets, which drives the allocation between stocks and gold. 100% probability of bull market means 100% stocks while 50% probabilty of bull market means 50% stocks and 50% gold.