Key Highlights

● Dow futures were up 0.02% at 52,521 while Nasdaq-100 futures fell 2.62%.

● Chevron reported third-quarter adjusted Earnings of $10.4 billion, or $5.28 a share.

● Health care rose 2.4% Thursday and hit a record high as defensives drew buyers.

● Price weighting limits the damage from a 7% drop in Amazon.

Dow futures were at 52,521 at roughly 8:03 a.m. ET Friday, up 9 points or 0.02%, in a market quote snapshot. Nasdaq-100 futures were down 2.62% and S&P 500 futures down 1.13% at the same time. Earlier reads were similar. One investor-data site had Dow futures up 0.05% around 5:36 a.m. ET, and a social investing platform called them roughly flat around 6 a.m. ET.

The Blue-Chip average is holding steady while Amazon (NASDAQ:AMZN) and Intel (NASDAQ:INTC) lead a broad technology selloff. Three forces explain why.

Energy earnings provide a lift

Chevron (NYSE:CVX), a Dow component, reported third-quarter adjusted earnings of $10.4 billion, or $5.28 a share, according to its Oct. 30 regulatory filing. Downstream earnings reached $4.9 billion. CEO Mike Wirth said the company "delivered strong operational performance and disciplined execution." One financial news site reported the shares up 1.70% in premarket trading at 7:41 a.m. ET.

Exxon Mobil (NYSE:XOM), which is not a Dow member but sets the tone for the sector, posted earnings excluding identified items of $17.51 billion, or $4.23 a share. It rose 2.09% in premarket trading, per the same report. With WTI crude at $104.20 after Iran said four tankers struck mines in the Strait of Hormuz, energy stocks have a tailwind.

The second force is a shift into defensive sectors. On Thursday, health care rose 2.4% and real estate 2.2%, according to market data, while technology fell 1.2%. One report said the health care sector hit a record high. That rotation helps the Dow, which holds UnitedHealth (NYSE:UNH), Johnson & Johnson (NYSE:JNJ), Amgen (NASDAQ:AMGN), Merck (NYSE:MRK), Procter & Gamble (NYSE:PG), Coca-Cola (NYSE:KO) and other defensive names.

Premarket data from a financial news service's pro tier on Friday showed staples such as PepsiCo (NASDAQ:PEP), General Mills (NYSE:GIS) and Kraft Heinz (NASDAQ:KHC) up roughly 2.5% each. The page's automated notes describe "defensive and Dividend buying," though it cautions that those notes may not be the direct cause of a price move.

The third Factor is arithmetic. The Dow is weighted by share price, not market value. Amazon is a Dow member and was down about 7% before the bell.

But in a price-weighted index its share of the average is far smaller than its share of the S&P 500. Nvidia (NASDAQ:NVDA) is also a member and was among the chip names down between 2% and 9%, per media reports. Intel, the day's biggest loser, is no longer in the Dow.

The Dow is not without weak spots. Caterpillar (NYSE:CAT) fell about 9% on Thursday after keeping its sales forecast, media reports said, and the average closed down 0.25% that day even as 23 of its 30 stocks rose, per market data.

Based on closing levels, the Dow was up about 2.8% for October through Thursday, ahead of the S&P 500's roughly 0.9% gain and the Nasdaq Composite's roughly 2.5% loss. A flat Friday would lock in a month in which old-economy blue chips clearly beat technology.

The offset depends on oil staying high and the tech selloff staying contained. A sharp Reversal in crude, perhaps on progress in Qatari mediation with Tehran, would take away the energy support. A deeper slide in Amazon, Nvidia and other big Dow tech names could also outweigh gains elsewhere.

What to watch

After the open, watch Chevron, Amazon and the health care heavyweights, which together will largely decide the Dow's direction. The Chicago PMI at 9:45 a.m. ET and Fed speakers at midday could move rate-sensitive names. Next week brings Apple (NASDAQ:AAPL)'s earnings on Monday, the midterm elections on Tuesday and the October jobs report on Friday.