Obrigado Lazarus. Estive entretanto a pesquisar e obtive essa confirmação no site da EDP.
Aqui ficam as cotações relevantes referentes ao 1º semestre de 1998:
Data Fecho Volume
02-01-1998 3.3780 3,729,395
05-01-1998 3.5680 5,559,334
06-01-1998 3.5440 3,756,658
07-01-1998 3.5060 4,839,420
08-01-1998 3.5300 5,109,053
09-01-1998 3.5250 2,497,899
12-01-1998 3.4960 3,675,952
13-01-1998 3.5250 4,357,778
14-01-1998 3.4930 3,694,420
15-01-1998 3.5200 3,206,895
16-01-1998 3.5440 4,777,322
19-01-1998 3.5590 2,109,236
20-01-1998 3.5780 3,721,731
21-01-1998 3.5730 3,911,761
22-01-1998 3.6200 3,894,417
23-01-1998 3.6390 5,604,301
26-01-1998 3.6710 3,020,061
27-01-1998 3.6990 4,106,202
28-01-1998 3.7340 3,472,696
29-01-1998 3.7440 4,044,787
30-01-1998 3.7080 3,593,162
02-02-1998 3.8320 4,653,123
03-02-1998 3.8320 4,950,644
04-02-1998 3.8320 3,615,963
05-02-1998 3.8290 2,168,173
06-02-1998 3.7790 2,926,139
09-02-1998 3.7550 4,036,653
10-02-1998 3.6670 3,807,623
11-02-1998 3.6500 3,501,896
12-02-1998 3.6100 4,078,407
13-02-1998 3.6100 2,664,426
16-02-1998 3.5830 1,879,321
17-02-1998 3.7360 4,092,424
18-02-1998 3.7540 3,347,314
19-02-1998 3.7630 3,334,531
20-02-1998 3.7760 6,937,008
23-02-1998 3.8320 10,203,948
25-02-1998 3.8940 6,036,826
26-02-1998 3.8170 4,880,346
27-02-1998 3.7740 2,777,774
02-03-1998 3.9230 8,685,173
03-03-1998 3.9650 5,748,432
04-03-1998 3.8800 6,712,050
05-03-1998 3.8220 4,260,232
06-03-1998 3.9080 5,217,283
09-03-1998 3.9370 3,510,872
10-03-1998 3.9150 3,103,699
11-03-1998 3.9080 3,823,796
12-03-1998 3.9280 3,905,882
13-03-1998 4.1240 9,868,719
16-03-1998 4.0710 4,257,592
17-03-1998 4.0770 3,688,125
18-03-1998 4.1000 2,342,947
19-03-1998 4.0860 2,827,245
20-03-1998 4.1380 4,502,076
23-03-1998 4.3300 7,034,835
24-03-1998 4.3730 6,041,768
25-03-1998 4.3910 4,172,084
26-03-1998 4.3680 2,509,776
27-03-1998 4.3110 3,020,066
30-03-1998 4.2530 4,174,094
31-03-1998 4.2100 4,719,214
01-04-1998 4.2960 4,206,622
02-04-1998 4.4060 7,862,756
03-04-1998 4.4890 4,506,325
06-04-1998 4.5930 5,945,206
07-04-1998 4.5980 8,211,747
08-04-1998 4.5790 3,384,908
09-04-1998 4.5700 3,024,268
14-04-1998 4.6990 6,186,878
15-04-1998 4.7900 7,813,556 - corresponde a 23,95 no preço antes do split
16-04-1998 4.7090 3,549,211
17-04-1998 4.7320 4,709,227
20-04-1998 4.6840 3,332,870
21-04-1998 4.7050 3,244,775
22-04-1998 4.7130 1,885,397
23-04-1998 4.7040 2,343,379
24-04-1998 4.6080 3,125,261
27-04-1998 4.3400 4,722,077
28-04-1998 4.6160 5,923,014
29-04-1998 4.5120 2,826,287
30-04-1998 4.5980 3,357,181
04-05-1998 4.6650 2,530,432
05-05-1998 4.5930 1,759,531
06-05-1998 4.5600 2,927,576
07-05-1998 4.4620 2,762,450
08-05-1998 4.4550 3,657,722
11-05-1998 4.4930 2,956,834
12-05-1998 4.4830 8,558,427
13-05-1998 4.3830 7,832,316
14-05-1998 4.3250 4,449,919
15-05-1998 4.4020 1,818,650
18-05-1998 4.3640 1,683,188
19-05-1998 4.6260 3,524,895
20-05-1998 4.6750 2,611,654
21-05-1998 4.6640 2,399,239
22-05-1998 4.6400 1,629,474
25-05-1998 4.6320 963,414
26-05-1998 4.6450 1,780,942
27-05-1998 4.5620 1,981,199
28-05-1998 4.6790 4,108,217
29-05-1998 4.5980 3,654,983
01-06-1998 4.5740 1,672,566
E já agora a fonte:
http://www.edp.pt/EDPI/Internet/PT/Grou ... Historical
http://ir1.euroinvestor.com/historicalq ... ormat=HTML