Here are some U.S. usages. In a a retail store, a cashier "cashes out" at the end of the day. Hopefully someone who's been a cashier can say more, but I think it means to physically remove the money from the till, count it, and check the total. In your use, it is figurative, but it carries a sense of totality and finality. It doesn't just mean to monetize, it means a decision to exit completely from a market. One might imagine an individual investor saying "I've just had it with REITs, No more. I'm back to even, so I'm going to cash out, take the money and run, sell them all and never look back." "Cash in" suggests that you are holding something that has a stated cash value, and that you have a right to redeem them at that value with the issuer. It means to monetize by redeeming with the issuer, as opposed to selling them on the market. If you are not familiar with U.S. savings bonds, they are _not_ marketable securities like regular bonds. They can't be sold to another investor. They can only redeemed directly with the Treasury. Therefore, it is natural to say you "cash them in." A very common use of the phrase is in a casino context. You buy chips with stated dollar values, make and settle your bets at the tables with chips, and cash in your chips when you are ready to leave.