Perf Week
Weekly Return
What is Perf Week (Weekly Performance)?
Perf Week (Weekly Performance) is a return measure that shows how much a stock's price has changed (in percent) over the most recent week (5 trading days). It's one of the shortest-term measures of price movement, and it's useful for spotting stocks that the market is paying attention to right now, or stocks that have just moved sharply. To put it simply, weekly performance is like stepping on a scale once a week to check your weight change. Day-to-day changes may not mean much, but looking at it week by week lets you spot a trend.
Key Terms (Korean-English)
Perf Week = Weekly Performance
Perf Month = Monthly Performance
Perf Quarter = Quarterly Performance
Perf Year = Yearly Performance
Momentum = the direction and strength of a stock's price move
Why Compare Returns Across Different Time Frames
Weekly performance only becomes truly useful when you compare it with returns over longer periods. If you only look at the weekly number, the time frame is so short that it's easy to be fooled by noise (temporary, meaningless swings).
Weekly vs. Monthly
If the weekly return is +5% but the monthly return is -3%, the stock bounced in the last week, but over the whole month it is still going down. You have to decide whether this short bounce is the start of a real trend reversal or just a technical bounce (a "Dead Cat Bounce").
Weekly vs. Yearly
If the weekly return is -8% but the yearly return is +45%, it's just a temporary dip inside a long-term uptrend. For long-term investors, that can actually be a buying opportunity. On the other hand, if the weekly return is +10% but the yearly return is -40%, the bounce is more likely just a short blip inside a long-term downtrend.
How to Read Perf Week
Strong positive weekly return (+5% or more)
A move of 5% or more in a single week shows very strong momentum. It could be driven by good earnings, positive news (like an FDA approval or a big contract), or a short squeeze. Momentum investors will pay attention, but chasing the stock after a big spike is risky. It's very common for a stock to drop again as traders take profits after a sudden rally.
Normal range (-3% to +3%)
Most large-cap stocks move within this range in a normal week. The average weekly move for the S&P 500 is roughly +/-1~2%. If there's no special event, a move in this range is normal and doesn't require a big reaction.
Strong negative weekly return (-5% or worse)
A drop of 5% or more in one week is a signal that market worries have grown. Causes can include weak earnings, a guidance cut, bad news, or a broad market selloff. For long-term investors, this can become a buying opportunity after analyzing the cause, but you have to be careful because it could also fall further.
Combining Perf Week With Other Return Measures
Momentum confirmed: weekly + monthly + quarterly all positive
When the weekly, monthly, and quarterly returns are all positive, strong upward momentum is confirmed. These stocks fit a Trend Following strategy. A good example is NVIDIA (NVDA), which had positive returns across every time frame during the AI boom.
Reversal signal: weekly positive, long-term negative
When a stock that has been falling for a long time starts to bounce on a weekly basis, it can be an early signal of a trend reversal. To check whether it's a real turnaround or just a short bounce, you should also look at trading volume, fundamental changes, and other factors.
Bearish continuation: weekly negative, long-term also negative
If returns are negative across every time frame, the stock is in a strong downtrend. Remember the saying "Never catch a falling knife." It's safer to wait until you see clear signs of a trend reversal.
Real-World Strategies (Scenarios)
Scenario 1: Sharp weekly rally after an earnings surprise
Suppose Tesla (TSLA) reports quarterly earnings that beat expectations by a wide margin and posts a Perf Week of +15%. In this case, the new information has already been priced in, so chasing the stock is risky. A smarter move is to analyze whether the earnings momentum can continue, then consider buying on the next pullback. Volatility is high for 1~2 weeks after an earnings surprise, so be careful.
Scenario 2: Sharp weekly drop caused by a broad market selloff
If the Federal Reserve (Fed) makes an unexpectedly hawkish comment and the S&P 500 falls -4% for the week, and Apple (AAPL) also drops -5%, that isn't a problem with any individual company; it's a market-wide mood shift. For long-term investors, a drop in a quality company with no change in fundamentals can be a buying opportunity.
Scenario 3: Using a weekly screen
Every week, check the stocks with the biggest weekly gainers and the biggest weekly losers by Perf Week. The big gainers can reveal new trends or themes, and the big losers can point to possible oversold opportunities. You can sort by Perf Week in Finviz's screener to find them easily.
Cautions
1. Be careful with too much short-term trading: If you trade based on weekly returns, trading costs (commissions, spreads) add up, and capital gains tax calculations get complicated. A large body of research shows that long-term investing outperforms short-term trading by a wide margin.
2. Separating noise from signal: Most weekly price moves are just meaningless noise. Real investment opportunities come from changes in fundamentals. Use weekly return only as a reference, and base your investment decisions on the company's underlying value.
3. Weekly returns of high-volatility stocks: High-volatility small-caps or meme stocks can easily move +20% or -20% in a single week. Don't get tempted by these extreme moves, and focus on stocks that match your own risk tolerance.
4. Holidays and shortened trading weeks: If a U.S. holiday cuts the trading week to 4 days, the comparison period for weekly returns changes. Especially around Thanksgiving and the turn of the year, trading volume is thinner and price moves can be different from usual.
Checklist: Things to Review When Using Perf Week
1. Identify the cause of the weekly return (earnings, news, overall market, etc.)
2. Judge it together with monthly, quarterly, and yearly returns
3. Check whether the move came with a change in volume (a sharp volume spike suggests the move is meaningful)
4. Compare the weekly return against other stocks in the same industry
5. Compare it with the overall market return, such as the S&P 500
6. When the weekly move is a sharp rally or drop, analyze the cause first instead of chasing the price
7. Don't react emotionally to short-term returns
Frequently Asked Questions (FAQ)
Q. If I keep chasing stocks with the highest weekly return, will I make money?
A. So-called "momentum strategies" are proven to work even in academic studies, but ultra-short-term weekly momentum is inefficient for individual investors because of trading costs and volatility. Medium-term momentum (3~12 months) tends to give more stable returns. Also, momentum strategies can suffer big losses when the trend reverses, so a stop-loss rule is essential.
Q. Is weekly return volatility larger during earnings season?
A. Yes. During the U.S. earnings season (mid-to-late January, April, July, and October), earnings reports are concentrated, and weekly returns of individual stocks swing much more than usual. It's common for a stock to move 5~15% in a single day on an earnings beat or miss, and that shows up directly in the weekly return. During earnings season, you should pay extra attention to weekly return swings.
Q. If a stock's weekly return drops by more than -10%, is it okay to buy?
A. It depends. A sharp drop caused by a broad market decline or short-term news can be a buying opportunity for a quality company. But if the drop is caused by a serious problem in the company's fundamentals (like an accounting scandal or the collapse of a core business), the stock can keep falling. You need to figure out the exact cause of the drop before deciding whether to buy.
Q. How can Korean investors make good use of weekly return data from the U.S. market?
A. Make it a routine to check the weekly return of your watchlist stocks and the stocks you own every weekend. Looking at weekly return together with that week's major news, economic data releases, and Fed comments helps you understand the market context. USStockToday makes it easy to check weekly return by stock.
Notes for Korean Investors
Information delay due to time difference: The U.S. market trades during Korea's night-to-early-morning hours, so the weekly return is finalized only by Saturday morning Korea time. Doing a weekend review is the most efficient approach.
Effect of exchange-rate moves: If you factor in moves in the won-dollar exchange rate on top of the weekly return, your return in Korean won will differ from the dollar-based return. For example, if the stock price is up 3% but the won strengthens (the exchange rate falls) 1%, your return in won is roughly +2%.
Be careful with weekly rebalancing: Adjusting your portfolio every week based on weekly returns is inefficient in terms of taxes (capital gains tax) and trading costs. For most individual investors, rebalancing 1~2 times a year is optimal.
Managing your emotions: It's easy to feel anxious if a stock you own drops -7% in a single week, but from a long-term investing perspective, these short-term swings are normal. The S&P 500 experiences a drawdown of 5% or more about 3~4 times a year on average. Avoiding emotional trading is the key to long-term returns.