High liquidity and short timeline will not give very good yields. You could look at short term Govt bills or CDs, but if interest rates go up this will be a bad idea.

If you think the overall market is going to go up, I'd recommend a brokerage account at Schwab, and buy a mix of SCHD and SCHA. Both pay dividends, which will give some level of return, and if you broker with Schwab there is no transaction fees to buy/sell their ETFs. These ETFs also have very low management fees. You could also look at a S&P index fund, again based upon where you think the overall market is headed. Most mutual funds will also be a poor choice given the short horizon you have listed in my opinion.

With your short time line (and assumed desire for liquidity), I don't think pure stocks are wise, as there isn't significant enough time (in my opinion) to research and identify undervalued offerings if you're not in the market full time. There is also the risk of significant loss here if you're not reasonably diversified or are in highly volatile securities.

Physical precious metals would be a wise choice if you think the market will go down/economic turmoil is incoming. Try to buy from private sellers to minimize premiums. Generic, non government bullion in large quantities would be ideal for short term holdings.

Just my .02, I'm curious to see what others are thinking.