The sales-value-at split-off method allocates joint cost based on each product's proportionate share of market or sales value at the split-off point. Under this method, the higher the market value, the greater the share of joint cost charged against the product. As long as the prices at split-off are stable, or the fluctuations in prices of the various products are synchronized (not necessarily in amount, but in the rate of change), their respective allocated costs remain constant. cornerstone 7.9 shows how and why to allocate joint costs using the sales-value-at-split-off method.