Viking Therapeutics Leads GGUS Higher as CRAK Slips

The Goldman Sachs MarketBeta Russell 1000 Growth Equity ETF (GGUS) was among Tuesday's strongest ETFs, up about 2.6% at one point, lifted by Viking Therapeutics (VKTX), which was up roughly 33.7% before easing to 37.70, a gain of 25.21% on the day as of 15:26 GMT.

Two single-stock moves did most of the work behind Tuesday's standout exchange-traded fund performance. The Goldman Sachs MarketBeta Russell 1000 Growth Equity ETF (GGUS) was running about 2.6% higher on the day, outpacing the broader ETF board, with Viking Therapeutics (VKTX) up roughly 33.7% and Vicor (VICR) also among the fund's strongest components, according to Nasdaq Markets.

By the last trade at 15:26 GMT, some of that heat had come off. Viking Therapeutics was quoted at 37.70, up 25.21% from a prior close of 30.11, after touching 41.14 and dipping as low as 34.44 during the session. Vicor was at 251.39, up 12.28% from 223.90, having traded between 229.20 and 256.42. GGUS itself was at 68.99, up 0.35% from 68.75, inside a narrow 68.96 to 69.07 band on the quote.

Why a broad growth fund moves on two names

GGUS tracks a Russell 1000 growth mandate — a wide basket of large- and mid-cap U.S. companies classified as growth rather than value. Funds like this are usually slow movers by construction: hundreds of holdings, each one a small slice, so no single position should be able to swing the whole thing. That is the point of owning the index rather than the stock.

What Tuesday demonstrates is the limit of that logic on any given day. When a component moves by a third, and a second component moves by double digits in the same session, the arithmetic of diversification stops damping and starts amplifying. A day-level outperformance of about 2.6% for a broad growth vehicle is a large gap versus the benchmarks, and it is the kind of gap that gets produced by concentrated idiosyncratic news rather than by a factor rotation.

The index backdrop makes the point. The S&P 500 proxy SPY was at $773.70, up just 0.03% from a prior close of $773.50. The Nasdaq 100 proxy QQQ was firmer at $745.28, up 0.51%. The Dow proxy DIA was the laggard at $517.52, down 0.43%. None of those is a growth melt-up. The market was mixed and tightly ranged; GGUS's advance was a stock-picking outcome that happened to sit inside an index wrapper.

What the intraday tape says about Viking

The headline figure and the closing-hours figure are not the same number, and the gap is informative. Viking's high of 41.14 against a last trade of 37.70 means the stock had given back roughly 8.4% from its session peak by the time of the quote — a retracement, not a reversal, since it was still up more than a quarter on the day. That pattern, a violent gap higher followed by a partial fade, is characteristic of a news-driven biotech move where fast money takes the first leg and later buyers get filled at worse prices.

The day range tells the same story from the other side: from 34.44 at the low to 41.14 at the high, the stock traversed 6.70 points intraday, a spread worth about 22% of the prior close. Traders holding an index product got the smoothed version of that; traders holding the stock got all of it.

Vicor's move was cleaner. A 12.28% gain to 251.39, equivalent to 27.49 points added to the prior close, with a last trade close to the session high of 256.42, suggests a bid that held through the day rather than an opening spike that leaked away.

The other mover: CRAK pointing down

CRAK was the day's counterweight, quoted at 64.45 against a prior close of 64.87 — a decline of 0.65%, or 0.42 on the price. The intraday low of 63.12 was well beneath the last trade, so the fund recovered some ground into the afternoon after a weaker morning; the session high of 64.48 sat barely above the quoted level, meaning CRAK never traded in the green during the period covered.

Small percentage declines in a themed fund are not usually the story on a day when something else has jumped 25%. They matter here because they show how differently narrow-mandate products behave from broad ones. A concentrated sector fund lives and dies on the fortunes of one industry; a growth index fund can be dragged upward by a handful of holdings having an outsized day. Investors who own both should expect exactly this kind of divergence and should not read it as a signal about the market as a whole.

What to watch from here

The first question for anyone looking at GGUS after a day like this is persistence. A one-session gain driven by two components does not change the fund's underlying composition or its long-run tracking behaviour. If Viking gives back the rest of its gain in the coming sessions, the ETF's relative outperformance will unwind with it, mechanically and without any new information about growth stocks generally.

The second is the spread between the intraday peak and where the stock actually settles at the close. Viking's fade from 41.14 is the number to revisit; a stock that closes near its low after a large gap frequently sees follow-through selling, while one that recloses toward the high has usually found real holders. At 37.70 the stock sat between those two poles.

The third is whether CRAK's soft session extends. A 0.65% dip is noise on its own. Repeated over a week against a flat S&P 500, it becomes a sector signal worth examining in its own right rather than a footnote to somebody else's rally.

All prices cited are intraday as of 15:26 GMT on Tuesday, 22 September 2026, with the market open. They will have moved by the close.

Key facts

• VKTX last trade: 37.70, +25.21% (as of 15:26 GMT, 22 Sep 2026)
• GGUS last trade: 68.99, +0.35% (as of 15:26 GMT); reported up about 2.6% intraday
• VICR last trade: 251.39, +12.28% from a prior close of 223.90
• CRAK last trade: 64.45, -0.65%, day range 63.12–64.48

Frequently asked questions

How much was Viking Therapeutics up on Tuesday?

Viking Therapeutics (VKTX) was reported up about 33.7% during Tuesday's session. By the last trade at 15:26 GMT it was quoted at 37.70, a gain of 25.21% against a prior close of 30.11. The stock traded as high as 41.14 and as low as 34.44 during the day, so the size of the gain depended heavily on when it was measured.

What is GGUS and why did it outperform?

GGUS is the Goldman Sachs MarketBeta Russell 1000 Growth Equity ETF, a broad fund tracking large- and mid-cap U.S. growth stocks. It outperformed other ETFs on Tuesday, up about 2.6% at one point, because two of its components moved sharply: Viking Therapeutics and Vicor, the latter up 12.28% to 251.39.

How did CRAK trade on Tuesday?

CRAK was lower, quoted at 64.45 as of 15:26 GMT against a prior close of 64.87, a decline of 0.65%. Its intraday range ran from 63.12 to 64.48, meaning it recovered from a weaker morning but did not trade above the prior close at any point during the period covered by the quote.

Were the broad market indexes up on Tuesday?

They were mixed and tightly ranged. The S&P 500 proxy SPY was at $773.70, up 0.03%. The Nasdaq 100 proxy QQQ was at $745.28, up 0.51%. The Dow proxy DIA fell 0.43% to $517.52. None of those moves explains the size of the gain in GGUS, which came from individual holdings.

Can two stocks really move a diversified index ETF that much?

Yes, on a single day. Diversification damps average volatility but does not cap it. When one holding gains roughly a quarter to a third and another gains more than 12% in the same session, their combined contribution can push a broad growth fund well ahead of the benchmark, even though each position is individually small.

Why do the reported percentage and the live quote differ for VKTX?

The 33.7% figure reflects where the stock traded earlier in the session; the 25.21% figure is from the last trade at 15:26 GMT. Viking hit an intraday high of 41.14 before easing to 37.70, so the move faded by several points during the day. Intraday quotes change continuously until the close.

Sources

• Tuesday's ETF Movers: GGUS, CRAK — Nasdaq Markets