In often brisk trading the prices have drifted lower, reflecting unease over the corporate split and the growing uncertainty about drug industry prospects. Some institutions feel that the Zeneca rights was too highly priced and the ICI rump is the more attractive investment.
Yesterday Zeneca shares fell 4p to 632p against the 682p when dealings started. The nil paid rights opened at 86p last week and fell a further 3p to 42p.
Zeneca's poor display has to some extent been masked by steady buying for the US market and, at least in some quarters, the suspicion that one of the leading European drug groups is discreetly attempting to put together a significant share stake.
A stake declaration is not required until the shares move from the grey market to full listing.
The ICI rump has been far more resilient, climbing from an opening of 569p to 621p.
As the newest drug share wilted, other leading drug stocks, for so long friendless and weak, showed further signs of perking up. Growing evidence that the Clinton administration will not be as tough on the industry as was at one time feared and more positive signals from some drug boardrooms seem to have ended the steady erosion of confidence.
Glaxo Holdings has strengthened since a well-received investment meeting last week. The shares recouped a further 14p to 655p. SmithKline Beecham rose 15p to 481p and Wellcome 16p to 755p.
Fisons rose 2p to 172p. There is a growing suspicion that the group is in Zeneca's takeover sights. Even if the former ICI group does not strike it could replace Fisons in the FT-SE 100 share index.
The index ended 11.1 points higher at 2,858.1 in lacklustre trading. Today's two expected rights issues, from Allied-Lyons and British Airways, and the looming Danish referendum restricted trading. The Bank of England's signalled objection to any move towards lower interest rates was another inhibiting influence.
Allied slipped 2p to 543p and BA, in often busy trading, dipped 6.5p to 297p.
Stores were firm, largely on hopes of a confident statement today from Marks & Spencer. The high street giant is likely to record a strong profits advance, with the market expecting pounds 725m against pounds 672.2m. Boots, Dixons, Kingfisher and Next were among those higher. Marks ended 6p to the good at 355p.
The Marks influence wafted over Northern Foods, one of its biggest and best-known suppliers. The shares put on 10p to 270p.
But takeover speculation also helped Northern. Some are convinced that a big food bid is being lined up. United Biscuits, up 7p to 421p, remains the favourite target. But Northern would also be an appetising swallow for an ambitious predator.
The boardroom upheaval at Tottenham Hotspur at last had an impact on the shares. They rose 14p to 103p on the various profit forecasts and the indication that Alan Sugar, the chairman, is prepared to pay 125p a share.
Amstrad, the subject late last year of a Sugar bid, fell 1p to 32p, reflecting the BT satellite link with BSkyB. BT gained 3p to 417.5.
Ratners, the hard-pressed jeweller, bounced back to favour, gaining 3p to 35.5p. But worries of more problems at the Alexon fashion group trimmed the shares 3p to 82p.
Building and related shares continued to feel the breezes from a more confident housing market. Blue Circle Industries rose 2p to 260p.
Hepworth, regarded by some as the most likely target for the cash- rich MB Caradon, edged forward 2p to 390p as some analysts made confident predictions following a visit to the group's French operations. But rights issue fears restricted the advance.
Banner Homes, firm recently, put on another 10p to 70p, prompting the company to suggest that the shares 'now more accurately reflect the potential of the business'.
Pilkington, up 1p at 129p, attracted attention following a five- year specialised glass deal with the US Chrysler group. It could be worth dollars 100m.
SG Warburg improved 28p to 701p. Credit Lyonnais Laing sharply lifted its 1994 profit estimate to pounds 267m from pounds 182m. Current-year results are due soon. The market expects up to pounds 160m.
TSB Group, on continuing speculation of a bid or the sale of the Hill Samuel merchant banking offshoot, put on 4.5p to 185p.
Gold shares again reflected interest in the bullion price. Greenwich Resources rose 1.5p to 19.75p and Monarch Resources 19p to 171p. Lonrho, however, ran into profit- taking, falling 4p to 113.5p.
Pittencrieff fell 16p to 273p in response to the success of its bid for Aberdeen Petroleum. The shares touched 403p earlier this year. Cairn Energy edged forward 1p to 64p. It raised pounds 723,000 by placing 1.16 million shares at 62p with institutions. The cash will be used for the Teredo Petroleum acquisition.
SHARES recovered an early fall and the FT-SE 100 index, at one time down 6.5 points, ended 11.1 higher at 2,858.1 The FT-SE 250 index rose 3.7 to 3,146. Turnover was 533.7 million shares with 30,271 bargains. The account ends on Friday with settlement on 1 June.
ANOTHER high-tech success. Shares of Division Group, a 3-D computer software group, enjoyed the anticipated spectacular debut, closing at 96p, with Seaq putting turnover at 10 million. Briefly the price touched 108p. They were placed by the stockbroker Henry Cooke Lumsden at 40p. In December Henry Cooke launched Tadpole Technology at a 65p placing level. The shares fell 20p to 287p yesterday.
SAATCHI & Saatchi, the struggling advertising agency, has been forced to defer repayment of a pounds 50m bank loan by two years, its 1992 annual report, out yesterday, says. The sum was due to be paid during this year and next, but has been put off because the recession has dragged on much longer than it expected. Saatchi has also renegotiated the terms of its loan conditions. The shares fell 1p to 173p.