Investec has upgraded its rating for global banking giant HSBC from 'reduce' to 'buy', highlighting the potential for dividend growth.Analyst Ian Gordon said that the bank has ruled out any further major value-destructive acquisitions - "misguided attempts to deploy surplus capital/liquidity which organic opportunities could not absorb" - which means that its surplus capital generation "requires a home".He said that while share buybacks aren't likely, HSBC's "dividend paying capacity is strong".Gordon said: "We are repeatedly told that an acceleration in loan growth will prove key to delivering consensus-beating earnings, and underpinning dividend growth. We believe that the exact opposite is true - we expect anaemic loan growth, coupled with a falling net interest margin, to deliver sub-consensus revenues and earnings. However, it is precisely such an outcome which reinforces our belief that HSBC will be 'encouraged' to sharply increase its payout."He said that this reason, combined with a "re-based" entry level, supports its new 'buy' call.The broker's target price for the stock has been raised slightly from 735p t o 740p.Nevertheless, the stock was down 2.05% at 677.9p by 11:20 on Thursday, in line with the wider market sell-off.