(Reuters) - U.S. stock index futures edged lower on Friday, taking a pause from the previous session's rally that set Wall Street's main indexes on track for weekly gains after the Federal Reserve took a pivotal stance on monetary policy earlier in the week.

The S&P 500 notched its eighth session of gains out of nine on Thursday and closed at an all-time high, which breached the milestone it logged in mid-July. The blue-chip Dow settled above the psychological level of 42,000 points and clinched a record high.

The indexes along with the tech-heavy Nasdaq are on track for weekly gains of over 1%. The S&P 500 is also up over 1% so far in the month, bucking the historical trend that showed September has been weaker for U.S. equities on average.

At 5:43 a.m. ET, Dow E-minis were down 12 points, or 0.03%, S&P 500 E-minis were down 14 points, or 0.24% and Nasdaq 100 E-minis were down 75 points, or 0.37%.

Risk appetite got a boost earlier in the week after the Fed kicked off its easing cycle with a large but expected 50-basis-point cut and assured that more were on the way. The central bank also projected a period of steady economic growth and low unemployment and inflation.

As economic data is light, investors will focus on remarks from Philadelphia Fed President Patrick Harker due later in the day for his insights on the central bank's outlook on policy and the economy.

Traders see a 59.1% probability that the Fed will stick to a 25 bps cut in November, as per the CME Group's FedWatch tool. Expectations are that rates will drop by 72 bps by year-end, as per LSEG data.

Investors will also brace for volatility due to "triple witching" - an event where options and futures linked to stock indexes, futures and single stocks will expire on the third Friday of the last month of the quarter.

Among top movers, FedEx slid 13% after the postal service company, often seen as a bellwether to the U.S. economy, reported a steep quarterly profit drop and lowered its full-year revenue forecast. Rival United Parcel Service slipped 2.4%.

Nike jumped 6.9% after the sportswear giant said that former senior executive Elliott Hill will rejoin the company to succeed John Donahoe as president and CEO.

The rebalancing of the main indexes are also expected. Dell dipped 0.7%, Palantir Technologies fell 2.4% with the stocks expected to join the S&P 500 before the market opens on Sept. 23.

Globally, investors mulled whether the world's dominant economy is set to boom or face a recession. Central banks in the UK and Japan took a more cautious stance on interest rates, days after the Fed's verdict.

Historically, equities have performed well in a rate cutting cycle as lower borrowing costs could ease pressures on corporate profits. However, the outlook appears bleak with the S&P 500's valuations high above its longterm average.