A pair of investors who say they hold about $2 billion in Apple stock are pushing the company to do more to protect its youngest users from the effects of digital technology.

In an open letter to Apple, the investors, the activist hedge fund Jana Partners and the California State Teachers’ Retirement System, voiced concerns that such technology might be hurting children and said Apple could help ease the damage even as it generates business.

“We believe that addressing this issue now will enhance long-term value for all shareholders, by creating more choices and options for your customers today and helping to protect the next generation of leaders, innovators, and customers tomorrow,” they wrote in the letter, dated Saturday.

The investors, whose combined holdings are small compared with Apple’s approximately $900 billion market value, cited research suggesting that the prevalence of digital devices, such as the laptops, tablets and smartphones Apple makes, may be negatively affecting children.