Trump’s 3,711 trades point to multiple stock-market strategies

President Donald Trump’s latest financial disclosure has drawn scrutiny for its astonishing scale: 3,711 trades, almost entirely in shares of companies across America, including many whose fortunes can turn on federal policy.

Collectively, they constitute an unprecedented burst of stock-market activity by a sitting president that has fueled fascination among the day-trading masses and prompted detractors to warn of insider-dealing.

But a review of the transactions, combined with interviews with investment experts, reveals trading so multifaceted it doesn’t easily lend itself to definitive interpretation. The patterns bear the hallmarks of overlapping portfolio-management strategies, often index-based and much of it likely automated, and all of it difficult to disentangle.

To a large extent, that conforms with the Trump Organization’s public explanation of the matter. It says the president’s holdings are independently managed by third-party financial institutions that control all investment decisions, including asset allocation, trading, rebalancing, and portfolio management. Trades are...