Publisher Reed Elsevier said, as expected, it should report a modest reduction in adjusted operating margin in 2010 due to a weak revenue environment and increased investment in legal markets. The group said advertising and promotion and certain other markets remain difficult although the rate of revenue decline is slowing as comparatives get easier.Business trends seen in the second half of 2009 are continuing in 2010, particularly with regard to late cycle effects in its relatively resilient professional markets.Late cycle effects and reduction in adjusted operating margin will most particularly impact the first half comparison. "The first half will also see approximately 8% dilution to adjusted earnings per share from the July 2009 equity placing; the second half comparison will be largely unaffected as the earnings dilution from the placing was reflected in the 2009 second half," it added.