NEW YORK (AFP) - The Dow added modestly to its record level in opening trading Wednesday, but the S&P 500 and Nasdaq both fell as the post-election stock rally showed signs of fatigue.

Five minutes into trading, the Dow Jones Industrial Average stood at 19,033.94, up 0.1 per cent.

The broad-based S&P 500 shed 0.3 per cent to 2,197.52, while the tech-rich Nasdaq Composite Index fell 0.5 per cent to 5,360.29.

US stocks posted records the last two days on rising hopes about pro-growth policies from Washington following the Republican election sweep. The Dow finished above 19,000 for the first time Tuesday.

But pharmaceutical stocks were in retreat after Eli Lilly announced the failure of a trial for a new drug to treat Alzheimer's Disease. Lilly plunged 14.9 per cent, while Pfizer lost 1.6 per cent and Merck 2.6 per cent.