re: Need help with a lump sum

Good for you man, if you are truly 30 with all that and you didn't have a big chunk handed to you then you truly hustled hard.

What's worst case scenario if the stock market dips 10%? You put less down or you wait to pay off your loan? Do you have to make a single lump sum payment on the commercial loan or can you simply not make a payment until then? If you simply can't make a payment until then but can anytime afterwards, then I'd consider investing a decent portion in equities say 60% and put the other 40% in a CD.

Lastly, have you looked into refinancing? I'd strongly look into getting a fixed rate with your large lump sum you will have. Or at least look into better terms. I'd go to the bank that has your current loan first, see if they will do any cheap deals for you. $300k lump sum on a $600k loan will usually make someone want to talk.