The following commentary comes from an independent investor or market observer as part of TheStreet's guest contributor program, which is separate from the company's news coverage.By Win Thin NEW YORK ( BBH FX Strategy) -- Turkey's central bank sold $750 million and bought Turkish lira in its daily auction Wednesday. It offered as much as $1.35 billion and received $1.83 billion in bids. On Tuesday the bank offered and sold $140 million and received $375 million in bids. On Monday, it offered and sold $50 million and received $140 million in bids. This clearly shows the intensification of forex activity. The central bank said that large dollar auctions may continue. The intensified intervention this week came as the dollar/Turkish lira currency pair (USD-TRY) made new highs for the cycle at more than 1.90. In the current environment, however, the most that the Turkish central bank should do is to provide two-way liquidity in the forex market and not to defend any particular level. We remain skeptical about this current bounce in sentiment and risk appetite, and we continue to believe that emerging markets remain vulnerable to further bouts of selling. In this environment, we think emerging-market currencies with weak fundamentals will continue to underperform. With EM reserve data being released now for September, we remind our readers that the drops reflect both forex intervention activity and valuation effects. That is, with the dollar significantly stronger across the board last month, reserves held in euros and other currencies were worth less in dollar terms. For instance, foreign reserves held in Australian dollars would have seen a 10% valuation loss in September. Turkey's foreign reserves stood at only $85.65 billion at the end of September, which we see as very limited firepower. Reserves have fallen about $7.4 billion (down 8%) from the July peak. According to the latest triennial survey by the Bank for International Settlements, the average daily turnover of the TRY was $14 billion in 2010. Burning through almost $1 billion per day is simply not a sustainable strategy. In a bit of a backdoor move, the central bank seemed to acknowledge this shortfall by doubling the amount of reserves that commercial banks are allowed to keep in foreign currency. It said that this move could boost central bank reserves by as much as $3.6 billion.