Small caps were clinging on to modest gains, though attention was directed elsewhere as the chancellor of the exchequer announced his budget.
The FTSE AIM 100 was up eight points at 3,361, while the AIM All-Share was barely changed at 711.
In contrast, the FTSE 100 index was up 37 at 6,177.
One of the big surprises in the chancellor's budget was the introduction of a sugar tax – though not for two years – on soft drinks.
AG Barr PLC (LON:BAG), maker of Irn-Bru, lost some of its fizz, shedding 4.5% at 529p, as did sector peer Britvic PLC (LON:BVIC), down 2.6% at 690.5p. PureCircle Limited (LON:PURE), the stevia ingredients producer, reacted positively to the development, as drinks makers could turn to its sweeteners as an alternative to sugar. Shares were up 3.9% at 400p.
Elsewhere, video editing group Forbidden Technologies PLC (LON:FBT) was still flying high, albeit off its high for the day of 15p. It was up 24% at 11.45p as it agreed a deal with computer titan Microsoft over its Forscene platform.
The Forbidden deal sees the US firm sell Forscene through its Azure Marketplace - an online store that provides configured software applications, developer services and data for use on the platform.
Sirius Minerals PLC (LON:SXX), the potash mine developer, was ahead by 10.8% to 23p as investors await the release tomorrow of the definitive feasibility study on its huge mine site in the North York moors.
On the flip side, Leni Gas & Oil PLC (LON:LGO) was down 14% at 0.257p as it took another step to restore its finances with a £1mln equity raise and more settlements in shares with its suppliers. In both cases, shares were issued at 0.25p. An additional £0.30mln placing is dependent on shareholder approval.
Sector peer IGas Energy Plc (LON:IGAS) was 6.2% lower. The onshore hydrocarbon producer saw revenues more than halve in 2015 to £25.1mln from £58.2mln the year before, although underlying earnings (EBITDA) only fell a little, to £18.3mln from £21.6mln.
Elsewhere in the resources sector, Pathfinder Minerals PLC (LON:PFP) shot up 30%. The company is in discussions to appoint a potential new local representative in Maputo to assist Pathfinder in its dialogue with the Mozambique Government over the restoration of its mining licences 760C and 4623C.
Stilo International Plc (LON:STL), down 14%, found the market hard to please. The software tools provider's full-year results disappointed, despite underlying earnings rising to £272,000 from £108,000 the year before.
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Top riser in London was video editing group Forbidden Technologies PLC (LON:FBT), which surged 50% to 13.88p, as it agreed a deal with computer titan Microsoft over its Forscene platform.
Small cap shares were easing higher as was FTSE100 ahead of the UK chancellor's budget speech. FTSE AIM 100 was up 0.22% to 3,360, while the FTSE AIM All share also gained 0.10% to 711.670.
Some commentators saw the markets as fairly quiet ahead of potential catalysts like the budget and Federal Reserve meeting.
The Forbidden deal sees the US firm sell Forscene through its Azure Marketplace - an online store that provides configured software applications, developer services and data for use on the platform.
Resource stocks were doing well.
A refinancing by DekelOil Public Limited (LON:DKL) cheered the market and is expected to positively impact profitability.
A loan for €8.69mln that was used to part fund its Ayenouan palm oil in Ivory Coast has been replaced by a new €9.15mln, seven-year facility, the firm revealed, sending shares 2.13% higher at 1.20p
Onshore US oiler Nostra Terra Oil and Gas PLC (LON:NTOG) rose over 15% to 0.10p as US crude prices rose almost 2% to US$37.04 a barrel.
Gold-focused mining firm Keras Resources (LON:KRS) was also up, rising 8.57% to 0.95p, just days after it inked its third gold tribute deal for Western Australia.
Sirius Minerals PLC (LON:SXX), the potash mine developer, raced ahead by 8.43% to 22.50p. Tomorrow, the group releases the results of the DFS on its huge mine site in the North York moors. Vast Resources (LON:VAST) was also doing well, up 9.38% to stand at 0.53p, despite a significant shareholder selling all of its holding.
On the flip side, Leni Gas & Oil PLC (LON:LGO) was down 5.08% at 0.28p as it took another step to restore its finances with a £1mln equity raise and more settlements in shares with its suppliers. In both cases, shares were issued at 0.25p. An additional £0.30mln placing is dependent on shareholder approval.
IGas Energy PLC (LON:IGAS) shares fell 7.69% to 15p as it revealed it has been successful in cutting back production costs to levels more manageable in the current oil price environment.
Operating costs for the year to Dec 31 reduced to $24.6 per barrel of oil equivalent, down from $34.6 per boe in the prior year.
IGas, a conventional oil and gas producer with unconventional upside, told investors that revenue fell to £25.1mln in 2015, down from 58.2mln in the year before.
Elsewhere, Netscientific (LON:NSCI) eased a tad - 1.14% to 87p - as it said Wanda, one of its core investments, had formed a scientific advisory board to guide the management team.