Complex sentence: Under these conditions investors can then be assumed to act rationally: their investment decision must be calculated or a loss is sure to follow; correspondingly, where an arbitrage opportunity presents itself, then arbitrageurs will exploit it, reinforcing this equilibrium.
Split into simpler sentences: Under these conditions investors can then be assumed to act rationally: their investment decision must be calculated or a loss is sure to follow. Also, where an arbitrage opportunity presents itself, then arbitrageurs will exploit it, reinforcing this equilibrium.