A 10-Day Losing Streak Has MasTec Stock Down 18%
Shares of MasTec (MTZ) have closed lower in each of the last 10 sessions, a cumulative decline of 17.9%. That erased about $3.2 billion from the company’s market value, which now stands at about $14.6 billion. The stock closed at $187.34 on Tuesday, October 20, its lowest close of the past year.
The Streak Next To The S&P 500
Returns for MTZ and the S&P 500 over the streak and the periods around it, all ending Tuesday, October 20 and including dividends:
| Return Period | MTZ | S&P 500 |
|---|---|---|
| 1 Day | -1.9% | 0.3% |
| 10 Days (Current Streak) | -17.9% | -1.3% |
| 1 Month (21 Trading Days) | -16.0% | -0.6% |
| 3 Months (63 Trading Days) | -47.6% | 3.1% |
| Year To Date | -13.8% | 13.7% |
| 1 Year (252 Trading Days) | -7.2% | 17.1% |
Is This Move About MasTec Or The Market?
Over the same 10 trading days, the S&P 500 returned -1.3% including dividends, so the slide is mostly MasTec’s own story rather than the market’s. Over the past three months the stock is down 47.6%, a window that includes the streak; over the other 53 sessions of that window it was down 36.1%.
Do The Fundamentals Justify The Selling?
On the fundamentals, revenue grew 23.5% over the last twelve months, against a median of 7.3% for S&P 500 Industrials stocks; its operating margin is 5.1%, versus a median of 17.6%; and the stock trades at 29.6 times trailing earnings against a median of 27.2. The read is mixed: revenue growth above the median on one side, margins below the median on the other.
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A Slide Like This Is Why Diversification Exists
Watching one stock fall day after day is the clearest lesson the market teaches about single-name risk. Whether this particular decline is an opportunity or a warning, the deeper point is the same: no one name should be able to do this to your portfolio.
The Trefis High Quality (HQ) Portfolio is built on that principle: roughly 30 businesses selected for consistent cash generation, strong margins, and resilient balance sheets, sized and rebalanced with rules. It has a track record of outpacing a benchmark that combines the S&P 500, the S&P MidCap 400, and the Russell 2000. Study the slide; spread the risk.