You should be extremely concerned. Equity firms are concerned with profit and a great way to increase profit is to reduce payroll.

It would be helpful to think about why you were acquired. Does your now former employer hold important patents or IP? Do you have key customers? Are the employees highly specialized and difficult to replace?

If it's the first or second, the risk of them winding down this company from an employment perspective much higher.

That's not to say it's all bad. When I went through a merger our health insurance improved. On the flip side, it became pretty clear within 3-6 months that the acquiring firm was calling the shots. Our offices were in different cities and it was also clear that my office was now "second tier".