FX.co ★ Stock market on August 20: S&P 500 and Nasdaq reverse

US equity indices closed higher yesterday. The S&P 500 rose 0.21%, the Nasdaq 100 added 0.16%, and the Dow Jones Industrial Average jumped 0.22%.

US Treasuries continued to rally after the US Treasury said it will at least double the size of its bond-buyback programs to curb long-term yields, an announcement that boosted sentiment and lifted Asian bond and equity prices. The dollar stabilized after sliding to a three-month low.

The 30-year US Treasury yield fell one basis point to 5.18% after a nine-basis-point drop on Wednesday. The 10-year yield declined by one basis point to 4.63%, extending a six-basis-point fall from the previous session.

The effect was global. Bonds in Japan, Australia, and New Zealand also rose after the US Treasury's statement, and the MSCI Asia-Pacific equity index gained 1.6%, ending a two-day losing streak. South Korea led the rally as the KOSPI jumped 5.5%. SK Hynix shares surged 12% on a share buyback announcement, and Samsung Electronics climbed 8.5%. The turn is striking given that the same names plunged more than 7% just a day earlier on rising yields.

In recent days global bond markets had been rocked as investors sought higher compensation for inflation risks and rising government debt, while Middle East tensions intensified price pressure. Nonetheless, analysts disagree on how durable the Treasury's actions will be, and most remain skeptical. Reed Capital said the buyback program signals serious Treasury concern about long-term borrowing costs, but that, as with interventions around the yen, the effect will be temporary.

How the operations will be financed merits separate attention. The Treasury did not specify, but it typically relies on the issuance of short-term bills to meet shifting funding needs.

Elsewhere, gold eased 0.8% to about $4,480 an ounce after reaching the highest level since early June. Bitcoin rose above $70,000 after President Trump urged Congress to pass a key crypto bill and the White House hosted industry leaders. Brent crude rose 0.4% to around $92 per barrel after Mr. Trump warned of an unprecedented economic campaign against Iran.

A technical picture for the S&P 500 suggests that buyers' immediate task today is to clear resistance at $7,718. That will show strength and open the way to $7,737. Controlling $7,756 will further cement the bulls' position. On the downside, if risk appetite ebbs, buyers must defend $7,698. A break there will quickly push the index back to $7,679 and open the road to $7,656.