Broadcom (AVGO) - Get Broadcom Inc. Report isn't backing down.

After Qualcomm (QCOM) - Get QUALCOMM Incorporated Report rejected the firm's $70 a share offer to acquire the mobile chipmaker -- a deal that would be one of the biggest tech M&A transactions in history -- Broadcom is looking to speed things along with a board change-up.

On Monday, Action Alerts PLUS holding Broadcom announced that it plans to nominate 11 independent directors to replace Qualcomm's entire board, at the firm's March 6 shareholder meeting, with directors who would be more favorable to approving a merger. Qualcomm maintains that the $60 cash and $10 stock offer undervalues the company -- which would become the third-largest chipmaker, if the deal goes through.

At current price levels, Broadcom's offer price represents an 8.7% premium to QCOM's current share price.

More significantly, that premium could get bigger if Qualcomm continues to play coy. After all, Broadcom's buyout offer basically snapped Qualcomm's shares out of an ugly rut that's been in play all year long. And now, shares of Qualcomm are back in make-or-break territory.

That puts shareholders in a potentially precarious position as QCOM management continues to try to make the case that one of the worst-performing big-cap semiconductor stocks on the market this year is grossly undervalued at a 31% premium to where shares traded before the bid was announced back in early November.

To figure out how to trade Qualcomm from here, we're turning to the chart for a technical look.

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The downtrend shares of Qualcomm had been stuck in for all of 2017 leading up to November is hard to miss -- so is the massive rally higher a month ago as Wall Street digested the acquisition offer. Shares initially consolidated sideways for a week before making a run toward higher ground. That attempt stalled out around the $70 level before rolling back over toward $64 support.

That price action is forming a pretty textbook example of a rounding top, a bearish reversal setup that looks just like it sounds. The rounding top is a price pattern that signals a gradual shift in control of shares from buyers to sellers -- and it triggers a clear-cut sell signal if the $64 level gets materially violated here. Shares are a stone's throw from that key level as I write.

Side indicators, like momentum, measured by the 14-day Relative Strength Index at the top of QCOM's chart, do still look constructive for shares. But if QCOM continues to rebuff its suitor without seeking a bigger payout from Broadcom or competing bids from other semis, then the current price setup indicates some near-term pain could be in store for shareholders again. Like with any M&A play, headline risk remains high -- a press release from either QCOM or AVGO could spark a big price move (like the 2% drop in QCOM shares Monday).

That should continue to make this trade exciting this winter. But if QCOM violates $64, investors should think about taking post-bid-announcement gains off the table and waiting for Qualcomm's price action to stabilize again before getting back in.

Qualcomm is in make-or-break mode right now -- and $64 is the line in the sand that shareholders don't want to see crossed this December.

This column originally appeared on Real Money, our premium site for active traders. Click here to get great columns like this from Jim Cramer and other writers even earlier in the trading day.

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