$A drops, Wall St rallies on mergers

The ASX is tipped to gain strongly at the open, despite weakness in the Australian dollar and iron ore sliding to $US52.69 a dry metric ton, down a further 0.85 per cent.

The US dollar rose and global equity markets surged on merger and acquisition activity among drugmakers on both sides of the Atlantic, while Chinese stocks hit a seven-year high on an ambitious government plan to create a modern Silk Road.