Once our investor has bought those 3 June IMM DM futures contracts (DM 125,000 each), he can say: "I am long 3 June IMM DM Futures"
If for some reason, he decided to sell 4 of the same contracts, how could the investor describe his new position?
a) "I am long -1 June IMM DM Future."
b) "I am long 7 June IMM DM Futures."
c) "I am short 1 June IMM DM Future."
Yes. Exactly. He was long 3 futures; now he sells 4 futures, closing his position on the original and assuming a short position on 1 future. Continue d) "I closed my position."