R.R. Donnelley & Sons Co., Chicago, is conducting an asset-liability study of its $1.8 billion pension fund, which should be completed by the end of the year, said Shaila Karim, manager of trust investments. It is too early to anticipate any recommendations resulting from the study, she said. The pension fund's asset allocation is 90% equity, 10% fixed income. Investment consultant Wurtz & Associates is assisting.