Your money will be safest in FDIC insured CDs, but it won’t hedge inflation, so even the best rate of 6% after inflation will yeild your 150K a nice Negative 11%.

Try crunching your tax numbers if you run a scenario where you pay down your mortgage with the 150K instead. Sum up your mortage interest for the year and divide by 3200. The result is the number of additional dependents you can claim on your W4 that will allow you to net more from each paycheck.

Then take the extra paycheck funds to hedge real inflation in your real life like making an accelerated payment of your mortgage or buying a hybrid or paying off revolving accounts.