From what I've seen, buybacks are often more about preventing dilution due to share-based compensation; they're effectively a tax-advantaged dividend. However, they can also be a sign of a company that has no better idea for spending their capital, which can indicate a decline in the ROI of their R&D. Could HP and IBM have done better with their cash over the last 10-15 years than buying back stock? Share repurchases seem to obfuscate with plausible deniability whether the intent is to return capital in a tax-advantaged way, or whether there's just a basic lack of faith in investing in new innovations.