re: What percentage of my total liquid assets should be in cash right now?

Other than for my everyday checking account needs I have $0 in cash.

However, I have a very wide-ranging mix of investments, a downturn in US equities shouldn't hurt all that much. And yes, I've been careful to invest in areas that tend to have low covariance in returns. For example, although I do have some non-US equity assets I deliberately picked a non-dollar hedged version to reduce the covariance with US equities and introduce foreign currency risk without actually getting into the forex market myself. The fund can do that less expensively than I can.