How the yen carry trade hits $SPY and $QQQ.1. Borrow cheap yen in Japan(Due to low interest rates)2. Convert to dollars3. Buy US stocks ( $SPY, $QQQ, etc.)4. Profit from the rate gapThat borrowed cash helped lift US stocks.If the yen strengthens, step 3 reverses. They sell $SPY/$QQQ to repay the yen loan. Stock prices can fall from that selling.This week: US and Japan jointly bought yen after a 40 year low. Yen rose. Carry trades got stressed.Weak yen = fuel for $SPY/$QQQStrong yen = selling pressure on $SPY/$QQQWatch USD/JPY with the indices.