Micron (MU) - Get Report stock fell hard on Friday, closing lower by 11.1% at $43.21.

The decline comes after the company reported its fourth-quarter earnings results and leaves Micron stock dangling above a key support level. If it gives way, it opens the gateway for lower prices. If it holds, a bounce could be in store.

Investors are likely frustrated with the post-earnings reaction, even though Micron beat on earnings and revenue. Even Wall Street analysts appear optimistic after the quarter, as they continue to believe the business is close to a trough.

While earnings of 56 cents per share beat estimates by 8 cents per share, they fell a whopping 84% from the prior quarter a year ago. Revenue is similar, with sales of $4.87 billion beating estimates by more than $300 million but sinking more than 42% year-over-year.

You can see why the market views this quarter as mixed, and it's reflected on the chart. Now at make-or-break territory, let's take a closer look at Micron stock chart.

Save 57% During Our Fall Sale. Join Jim Cramer's Action Alerts PLUS investment club to become a smarter investor. Click here to sign up and save!

Trading Micron Stock

Daily chart of Micron stock.

Back in March and April, Micron stock was putting in a series of higher lows, but kept getting rejected from the $43.75 to $44.75 level. Ultimately, shares failed to break out, falling precipitously to the low-$30s.

This mark was again a focal point in July and August, before MU stock erupted over it in September. Now, though, Micron is right back into this area. The hope from bulls is that former resistance will now act as current support.

With Friday's drop, Micron stock gapped below both the 50-day moving average and 78.6% retracement. It's also making new lows for the month as well. As it sits on the bottom of prior range resistance, it's also right down into uptrend support (blue line).

Put simply, this is must-hold territory for the stock.

If support fails, it immediately opens the door to the 61.8% retracement near $42.60 and the 50-day moving average near $41.50. However, should MU stock continue lower -- losing its 200-day moving average near $40.15 and its 50% retracement at $42.60 -- then it could open to the door to much larger losses, as we saw earlier this year.

As always, though, remember to take it one level at a time.

Should the $43.75 to $44.75 area hold as support, we need to reconsider Micron stock's upside levels.

In that case, I want to see MU stock reclaim its 78.6% retracement and 50-day moving average near $46.10, then fill its post-earnings gap back up toward $48. Above that puts the $51 highs on the table.

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