The weekly chart for the Dow Jones Industrial AverageI:DJI ended last week negative. The weekly chart for Dow transports is neutral. The weekly charts for the S&P 500 I:GSPC , the Nasdaq Composite I:IXIC and Russell 2000 are positive but overbought.

Here's how to read the weekly charts to determine when a bear market scenario becomes realistic.

The weekly charts show a red line through the price bars. which is the key weekly moving average (a five-week modified moving average). The green line is the 200-week simple moving average considered the "reversion to the mean." The study in red along the bottom of the chart is weekly momentum (a 12x3x3 weekly slow stochastic), which scales between 00.00 and 100.00, where readings above 80.00 indicates overbought and readings below 20.00 indicates oversold. A negative weekly chart shows the stock below its key weekly moving average with weekly momentum declining below 80.00 in a trend towards 20.00.

Remember that stochastic readings can help investors judge when to reduce long positions. The 12x3x3 weekly slow stochastic is based upon the last 12 weeks of data - Each week's high, low and last prices. This measure of momentum rises as new weekly highs continue and with the last prices closer to the highs. When this pattern changes and weekly last prices are closer to the lows, the stochastic reading will begin to decline providing an early warning to reduce holdings.

Here are the weekly charts for the exchange-traded funds that best represent the five major U.S. equity averages.

Here's the weekly chart for the SPDR Dow Jones Industrial Average ETF (DIA) - Get Report , aka Diamonds.

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Courtesy of MetaStock Xenith

Diamonds trades near $182, up 4.8% year to date after setting its all-time intraday high of $186.88 on August 15.

The weekly chart for Diamonds has been downgraded to negative with the exchange-traded fund below its key weekly moving average of $182.64 and well above its 200-week simple moving average of $165.77. The weekly momentum reading fell to 74.13 last week down from 80.67 on Sept. 16 moving below the overbought threshold of 80.00.

Investors looking to buy Diamonds should do so on weakness to 179.84, which is a key level on technical charts until the end of September. The $181.58 level remains a pivot or magnet until the end of September.

Investors looking to reduce holdings should wait a week as new levels for October and the fourth quarter come to light.

Here's the weekly chart for SPDR S&P 500 ETF Trust (SPY) - Get Report , aka Spiders.

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Courtesy of MetaStock Xenith

Spiders trades at $216, up 5.9% year to date and set its all-time intraday high of $219.50 on August 15.

The weekly chart for Spiders returns to being positive but overbought with the ETF above its key weekly moving average of $215.36 and well above its 200-week simple moving average of $190.35. The weekly momentum reading slipped to 81.08 last week down from 86.41 on Sept. 16, down from 90.57 on Sept. 9, down from 93.70 on Sept. 2 and down from 94.14 on August 26, still above the overbought threshold of 80.00. This reading will likely be below 80.00 this week.

Investors looking to buy Spiders should do so on weakness to $212.02 and $211.71, which are key level on technical charts until the end of September.

Investors looking to reduce holdings should wait a week as new levels for October and the fourth quarter come to light.

Here's the weekly chart for the PowerShares QQQ Trust ETF (QQQ) - Get Report , dubbed QQQ.

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Courtesy of MetaStock Xenith

QQQ trades around $118, up 5.8% year to date after setting an all-time intraday high of $119.22 on Sept. 22.

The weekly chart for QQQ remains positive but overbought with the ETF above its key weekly moving average of $115.93 and well above its 200-week simple moving average of $94.78. The weekly momentum reading slipped to 86.42 last week down from 86.66 on Sept. 16, down from 87.48 on Sept. 9 and down from 89.20 on Sept. 2.

Investors looking to buy QQQ should do so on weakness to $107.59, which is a key level on technical charts until the end of September.

Investors looking to reduce holdings should wait a week as new levels for October and the fourth quarter come to light.

Here's the weekly chart for the iShares Transportation Average ETF (IYT) - Get Report .

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Courtesy of MetaStock Xenith

The transports ETF trades at $143, up 6.2% year to date and is just 2% below its April 20 high of $146.07, and still in correction territory 14.8% below its all-time intraday high of $167.80 set on Nov. 28, 2014.

The weekly chart for the transportation ETF remains neutral with the ETF above its key weekly moving average of $141.25 and above its 200-week simple moving average of $135.81. The weekly momentum reading ended last week at 79.85 last week down from 81.48 on Sept. 16 and down slightly from 82.31 on Sept. 9. The momentum reading slipped below the overbought threshold of 80.00.

Investors looking to buy the transportation ETF should consider doing so on weakness to $136.24, which is a key level on technical charts until the end of 2016.

Investors looking to reduce holdings should wait a week as new levels for October and the fourth quarter come to light.

Here's the weekly chart for the iShares Russell 2000 ETF (IWM) - Get Report .

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Courtesy of MetaStock Xenith

The small-caps ETF trades near $125, up 10.8% year to date and set its 2016 high of $125.88 on Sept. 23.

The weekly chart for the small cap ETF remains positive but overbought with the ETF above its key weekly moving average of $122.07 and well above its 200-week simple moving average of $111.02. The weekly momentum reading ended last week at 87.37 slipping from 89.88 on Sept. 16, slipping from 92.34 on Sept.9 and from 94.81 on Sept. 2, becoming less overbought above the threshold on 80.00.

Investors looking to buy this ETF should do so on weakness to $115.45 and $112.44 which are key levels on technical charts until the end of September.

Investors looking to reduce holdings should wait a week as new levels for October and the fourth quarter come to light.

This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.