Trading desks were buzzing Friday after an unusual currency trade unsettled markets moments before the release of the monthly employment report.

Reflecting the degree to which global financial markets have become interconnected, the chatter about a sudden jump in the yen against the dollar wasn't contained to the foreign-exchange world. Within seconds, stocks and bonds also started to move in what traders said likely were computer-driven buy-and-sell orders generated in response to the move in the currency markets.

Traders...