Nasdaq Retakes Its 50-Day Line as AMD Jumps 6.4%

The S&P 500 and Nasdaq closed back above their 50-day moving averages on Sept. 17, 2026, with the Nasdaq 100 tracker QQQ up 1.73% at $716.92, as AMD gained 6.36% to 545.09 and Moderna rose 8.55% to 158.07 in a second-day reaction to the Federal Reserve.

The second session after a Federal Reserve decision is often where the real verdict gets delivered, and on Thursday it came in bullish. The S&P 500 and the Nasdaq composite both closed back above their 50-day moving averages, Treasury yields eased, and two of the market's most-watched momentum names — chipmaker AMD and vaccine developer Moderna — broke out hard enough to register as technical buy signals, according to Investor's Business Daily. Dow futures, however, slipped after the close, a reminder that the rebound is not uniformly shared.

What the closing tape actually showed

The index-tracking funds tell the story cleanly. As of the last trade at 20:00 GMT on Thursday, Sept. 17, 2026, the SPDR S&P 500 ETF (NYSEARCA: SPY) finished at $762.60, up 1.13% from the prior close of $754.05, having traded between $759.96 and $763.57. The Invesco QQQ Trust (NASDAQ: QQQ), which tracks the Nasdaq 100, closed at $716.92, up 1.73% from $704.72, with a day range of $713.32 to $718.04. Both closed near the upper end of their session bands — the mark of a day that was bought into the bell rather than sold.

The SPDR Dow Jones Industrial Average ETF (NYSEARCA: DIA) lagged, closing at $518.35, up 0.61% from $515.22 in a $516.55 to $520.67 range. That gap between the Dow's advance and the Nasdaq's is the single most useful number of the day: leadership sat squarely in technology and high-beta growth, not in the industrial and financial heavyweights that dominate the price-weighted Dow. The softness in Dow futures after hours fits the same pattern rather than contradicting it.

Why the 50-day line matters more than the percentage

The 50-day moving average is the average closing price over the previous 50 sessions. It is not magic, but it is the line institutional desks and trend-following systems most often use to define whether an index is in an intermediate uptrend or a correction. Losing it tends to invite selling on rallies; regaining it tends to invite buying on dips. Recovering it on both the S&P 500 and the Nasdaq on the same session, with volume-led breadth in the growth complex, is the kind of signal that changes the posture of money managers who spent the prior stretch trimming exposure.

The bond market gave the move its foundation. Treasury yields fell, which mechanically lifts the present value of distant earnings and therefore disproportionately helps the long-duration growth names concentrated in the Nasdaq 100. That is the plumbing behind the QQQ outperforming SPY, and SPY outperforming DIA, in a single tidy sequence.

AMD and Moderna clear their buy points

AMD closed at 545.09, up 6.36% from the prior close of 512.50, after ranging from 527.60 to 551.42. That is a gain of 32.59 points on the session — an illustrative arithmetic step, not a figure reported separately — and the close landed in the top quarter of the day's range, which is what chart-based investors want to see from a breakout rather than a spike that fades.

Moderna was the stronger of the two in percentage terms, closing at 158.07, up 8.55% from 145.62, with a session range of 149.50 to 161.96. The advance works out to roughly 12.45 points, again an illustrative calculation from the closing data. Moderna's move is notable because biotech has generally needed lower discount rates to work; a day of falling Treasury yields is exactly the environment in which unprofitable or lumpy-cash-flow drug developers get re-rated fastest.

In chart terms, a "buy signal" or "buy point" is a price level — usually the high of a prior consolidation — that a stock has to clear on strong volume for a technician to treat the trend as resumed. Both names cleared theirs on Thursday. What matters next is the follow-through: breakouts that surrender their trigger level within a few sessions are the ones that turn into losses, which is why disciplined users of this framework pair the entry with a fixed exit rule rather than a conviction.

SpaceX enters the conversation

The third name flagged alongside AMD and Moderna was SpaceX, which sits in a different category entirely from the two listed stocks. It is not a company retail investors can buy through an ordinary exchange order the way they can the chipmaker or the biotech, and it carries no exchange-qualified ticker. Any exposure runs through vehicles and structures rather than a direct share purchase, which means the technical language of buy points translates imperfectly. Investors reading a SpaceX "buy signal" should be clear about what instrument they are actually transacting in before treating it as equivalent to a breakout in a liquid large-cap.

What to watch from here

Three things determine whether Thursday was a turn or a bounce.

• Whether the 50-day lines hold. Regaining a moving average and then losing it again within days is a classic failed-rally signature. Holding above it on a pullback would confirm the recovery.
• Whether yields keep cooperating. Thursday's advance was built on falling Treasury yields. If that reverses, the same duration math that lifted the Nasdaq 100 and Moderna works against them just as quickly.
• Whether breadth widens. The Dow's 0.61% gain against the Nasdaq 100's 1.73% shows a narrow, growth-led tape. A durable uptrend usually needs the cyclical and financial cohort to join rather than trail.

The softer Dow futures after the close are the honest counterweight to an otherwise strong session. Futures move on overnight news flow and tell you little about the next full session, but they do signal that the enthusiasm was not evenly distributed. For now the message from the closing bell is that the post-Fed reaction has been read as friendly, that the index trend lines have been reclaimed, and that leadership is concentrated in exactly the places lower yields reward most.

None of this is a recommendation. A breakout is a starting condition, not an outcome, and both AMD and Moderna finished Thursday having already moved a long way in a single session — which is another way of saying the risk of chasing is highest precisely when the chart looks best.

Key facts

• Nasdaq 100 (QQQ): $716.92 at the close, +1.73%, as of 20:00 GMT Sept. 17, 2026
• S&P 500 (SPY): $762.60 at the close, +1.13% from $754.05
• AMD: 545.09 last traded, +6.36% from 512.50, range 527.60–551.42
• MRNA: 158.07 last traded, +8.55% from 145.62, range 149.50–161.96

Frequently asked questions

What is a 50-day moving average and why does regaining it matter?

It is the average closing price of the previous 50 trading sessions, redrawn each day. Traders use it to judge whether an index is in an intermediate uptrend. Below it, rallies tend to be sold; above it, dips tend to be bought. The S&P 500 and Nasdaq both closed back above that line on Sept. 17, 2026.

How much did AMD and Moderna gain on Sept. 17, 2026?

AMD last traded at 545.09, up 6.36% from its prior close of 512.50, with a session range of 527.60 to 551.42. Moderna last traded at 158.07, up 8.55% from 145.62, ranging from 149.50 to 161.96. Both closed in the upper portion of their day ranges.

Why did the Nasdaq outperform the Dow?

Treasury yields fell during the session. Lower yields raise the present value of earnings expected far in the future, which disproportionately benefits long-duration technology and biotech names concentrated in the Nasdaq 100. The Dow 30 tracker DIA rose 0.61% while the Nasdaq 100 tracker QQQ rose 1.73%.

What does a 'buy signal' mean in this context?

It is chart terminology. A buy point is typically the high of a prior consolidation range; clearing it on strong volume is read as the trend resuming. It is an entry condition, not a forecast, and technicians normally pair it with a predefined exit level in case the breakout fails.

Can retail investors buy SpaceX shares directly?

No. SpaceX is not listed on a public exchange and has no exchange ticker, so it cannot be purchased with an ordinary brokerage order the way AMD or Moderna can. Exposure runs through indirect vehicles and structures, which carry different liquidity, pricing and fee characteristics than listed equity.

Why were Dow futures falling if stocks rose?

Futures trade nearly around the clock and reprice on overnight news, so they can diverge from the prior session's close. The decline signalled that enthusiasm was not evenly spread across the market, consistent with the Dow's smaller 0.61% gain versus the Nasdaq 100's 1.73% advance.

Sources

• Dow Jones Futures Fall After S&P 500, Nasdaq Rebound Above Key Level; Moderna, AMD, SpaceX Flash Buy Signals — Investors Business Daily

Photo: Orlando105 · BY-SA 3.0 — source