Marketwatch reports that Reed Elsevier was a top decliner Tuesday, down 2.8% while Pearson shares declined 0.4%. Shares in Reed Elsevier declined as analysts noted that the positions held by both companies in the U.S. educational publishing market mean the deal will be investigated by regulatory authorities, and may not close until the first half of next year.

“The market shares of Reed/Harcourt and Houghton Mifflin Riverdeep are approximately 20% and 15% and, accordingly, the transaction will be investigated,” said analysts at Numis Securities. Analysts at Bear Stearns noted: “Riverdeep has suddenly become the No. 1 U.S. schools publisher with a market share of approximately 33%, overtaking Pearson at 37% and McGraw Hill at 22%.”