The markets took a swan dive earlier in the year and I believe that one reason was the move to a high probability that an anti-free trader would be president.
Hilary, Bernie, and the Donald are all calling for an end of free trade with other countries. Wall Street believes that means that the economy in the US and elsewhere will suffer. Thus, sell stocks now.
The market is rebounding as there now appears a stronger anti-Trump movement and thus lessens the threat to free trade that the Donald presents. Still, the Democrats will be anti-free trade in the presidential election.