Just as the increasing speed of technology disruption means tech executives must think through business strategy faster than ever, shareholders' lives move faster, too. They cannot afford to wait as long as they might have for investment returns. So tech execs need to be a lot more proactive in reviewing their own business portfolios -- and acting on the results -- before a value-seeking outside activist shareholder arrives to do it for them.

Of course, this is a generalization. Our latest quarterly global tech M&A update report, for the fourth quarter of 2015, shows that tech divestments soared last year to more than 500 deals, two-thirds higher than the 300 or so we counted in 2014. They were not all small; at least a half-dozen topped $1 billion, with Symantec's (SYMC) - Get Report Veritas divestment at the top of the list.

Activists did play a role initiating some of those deals, but others were initiated by tech executives who truly understand how the constant evolution of disruptive technology demands continuous portfolio review and fast, decisive action. A handful of incumbent tech companies are reshaping their entire businesses through divestment and M&A (think Nokia).

But activist investors are not content to let tech companies manage their portfolio review process on their own schedule, as opposed to the market's. Activist activity is likely to continue increasing -- a prospect that should be much higher on the list of challenges keeping tech executives awake at night.

We know it should be higher because of a disconnect we discovered when we analyzed tech respondents' results in EY's recently released Global Corporate Divestment Study. We found, for example, that 39% of technology companies say they are only moderately prepared for activist threats, and 17% are not prepared at all.

We also found that tech companies are not reviewing their portfolios often enough to keep pace with technology disruption and, even when they do, they don't always analyze and act quickly enough on the results. Half the tech respondents review their business portfolios only once a year; only 7% do so quarterly. Furthermore, 42% say their top challenge in implementing portfolio review findings is lack of time and resources to analyze the results, figure out what to do and do it.

All this is what culminates in the generalization that tech companies are too reactive about shareholder activism. It's not that activism is bad -- consider the shareholder value it often creates. But a great tech management team will create that value for shareholders apart from outside influences. In that way, their business visions won't derail.

Creating this value requires proactive analysis and immediate action. In the current fast-moving environment, anything less is inadequate.

Questions? Please contact me at globaltechnologysector@ey.com.

The views reflected in this article are the views of the author and do not necessarily reflect the views of the global EY organization or its member firms.