You can use the column command:
me@home$ column -t output.txt
CHAR.L 96.88 -6.75 (-6.49%)
MXP.L 12.62 -1.00 (-7.41%)
NEW.L 7.88 -0.75 (-8.57%)
AGQ.L 17.75 -0.62 (-3.40%)
RMP.L 13.12 -0.38 (-2.75%)
RRR.L 3.35 -0.20 (-5.71%)
RRL.L 7.95 -0.15 (-1.85%)
SOU.L 1.73 -0.10 (-5.22%)
YELL.L 5.47 -0.04 (-0.73%)
AMC.L 9.75 -0.01 (-0.05%)
PLU:USOP 95.40 0.00 (+0%)
BP-.L 452.10 0.95 (+0.21%)
SXX.L 29.00 1.50 (+5.41%)
LLOY.L 26.78 1.64 (+6.52%)
DES.L 23.62 2.25 (+10.34%)
GKP.L 171.62 4.50 (+2.69%)
XEL.L 83.75 5.00 (+6.33%)
BARC.L 190.57 9.80 (+5.43%)
RKH.L 251.62 12.00 (+5.02%)
UKX.L 5529.21 45.44 (+0.83%)