How are firms in the current market environment (2013- present) returning cash to stockholders, and what factors are impacting their decision-making? How has the market reacted to these decisions?

3 answers

As always, stockholders make money when the company makes good profits. For many companies profits tend to be short sighted and don't plan well for the future. The market keeps rising.
Many stockholders are making investments for other people, such as the people who manage teachers' retirement funds. When the market rises and the funds see increases, they can use the money earned to 1) pay the retirees' pensions and/or 2) reinvest the money to continue the good returns for use in the future. One such fund is this: https://www.calstrs.com/
factors are impacting their decision-making<<

It is always a risk vs reward decision. Whatever political, economic, or social things that are going on, and MIGHT go on in the future, affects risk and reward.