Liquidity

Liquidity is how quickly an asset can be turned into cash without losing value. Both halves matter. If you had to dump it in a hurry and accept a poor price, that is not liquidity.

Assets fall along a spectrum. Cash and deposits sit at the top. Listed stocks and ETFs are close behind, sellable in seconds during market hours. Real estate can take months to sell, and private shares or artwork are far down the scale, where simply finding a buyer is the work.

Illiquid assets usually offer somewhat higher expected returns in compensation, since you accept having money tied up and being unable to sell on demand. So when a product advertises a high return, it is worth asking whether that return pays you for taking risk or for giving up liquidity.

In personal finance, liquidity is a safety mechanism. However large your assets, if all of them sit in property and long-dated products, a sudden need for cash forces you to sell at a loss or borrow in a hurry. The advice to keep three to six months of expenses instantly accessible is not about giving up returns. It is about making sure you never have to sell everything else at the wrong moment.