Why Did US Bank Stocks Plunge This Week? BofA's Warning Is Just the Trigger; Inflation Is the "Invisible Killer"

Title context: Why Did US Bank Stocks Plunge This Week? BofA's Warning Is Just the Trigger; Inflation Is the "Invisible Killer" Text: The Federal Reserve raised interest rates on Wednesday as expected and signaled a hawkish stance that further rate hikes may be possible later this year. The KBW Bank Index fell 2.9% that day, its largest single-day drop since February, with its weekly decline widening to 5%. This week's selloff in bank stocks was the result of multiple pressures converging: cautious earnings guidance from Bank of America Corp (BAC.US) CEO Brian Moynihan directly ignited market concerns about weakening banking fundamentals, while the deeper causes point to persistently stubborn inflation, abnormal changes in the interest rate structure, and uncertainty in global debt markets. Direct Trigger: BofA CEO's Cautious Guidance Sinks the Sector The immediate trigger for this week's bank stock selloff came from remarks by Bank of America Corp CEO Brian Moynihan at a Barclays industry conference. Moynihan said the bank's third-quarter trading revenue is expected to be "roughly flat" compared with the same period last year, a forecast that stands in sharp contrast to Wall Street's strong trading performance in the first half. Moynihan expects third-quarter investment banking fee revenue of approximately $1.6 billion to $1.8 billion, while analysts had previously expected close to $2 billion. After Moynihan made those comments, Bank of America Corp shares fell as much as 6% intraday on Monday, the largest intraday drop since April last year, before closing down 5.14%. Shares of other Wall Street majors, including Goldman Sachs Group, Inc. (GS.US) and Morgan Stanley (MS.US), also came under pressure. It is worth noting that Moynihan explicitly pointed out that uncertainty in the interest rate environment is currently a key factor affecting capital markets activity. Only when companies have greater certainty about future financing costs are they more willing to make debt issuance decisions. In other words, the current problem is not just the level of interest rates themselves; sharp rate volatility is also suppressing corporate financing willingness and banks' capital markets businesses. Deeper Root Cause: Sticky Inflation Squeezes Bank Net Interest Margins from Both Ends The reason BofA's earnings warning triggered such a strong market reaction is that it exposed a deeper problem: persistently above-expected inflation is pushing interest rates higher in a way that is unfavorable to banks. The source of this inflation cycle can be traced back to the outbreak of the U.S.-Iran conflict about seven months ago. The conflict caused a global energy price shock, with oil prices surging sharply and quickly feeding through into overall prices. The Federal Reserve's preferred inflation gaugethe Personal Consumption Expenditures Price Index (PCE)jumped from less than 3% in February to more than 4% in May, while core PCE, which excludes food and energy price volatility, also briefly climbed to 3.5%. Although both have since retreated, headline PCE remains above 3.5% and core PCE is around 3.3%, far above the Fed's 2% target. The key reason inflation weighs on bank stocks is its distortion of the interest rate structure. Fixed-income investors view inflation as a loss of future purchasing power for their money, and when inflation expectations rise, they demand higher returns as compensation. This pushes up long-end ratesthe 10-year U.S. Treasury yield breaking above 5% this week is a direct reflection of rising inflation expectations. In the view of Seeking Alpha contributor Jeremy LaKosh, the core of the problem lies in banks' profit model. Banks borrow in the short-term market and lend in the long-term market, earning the spread between the twothe net interest margin. In a normal rate-hiking cycle, rising short-term rates drive up loan rates, and banks' net interest margins often widen accordingly. But this cycle is completely different. The U.S. Treasury is trying to push down long-end rates through operations that "sell short-dated debt and buy long-dated debt." Data show that since the last Fed meeting, long-end U.S. Treasury yields have risen by about 15 basis points, while 2-year to 5-year Treasury yields have risen by more than 40 basis points. Although the U.S. Treasury's operations have achieved some results, it still needs to issue short-term bonds to raise funds, which in turn pushes short-end rates even higher. This means banks' short-term funding costs are rising rapidly, but the yields on long-term loans are being suppressed by the U.S. Treasury's market operations. Borrowing costs are rising quickly while lending returns are rising slowly, net interest margins are clearly being compressed, and this will ultimately drag on bank profitability. Pressure on Bank Stocks Remains: Rate Hikes Fail to Ease Inflation Worries, Rate Volatility Becomes the Core Variable The Federal Reserve raised rates by 25 basis points on Wednesday as expected to a range of 3.75%4.00%, the first hike since July 2023, and signaled that further increases may be possible later this year. But for bank stocks, the key is not the rate hike itself, but investors' concern that it will fail to effectively bring down inflation expectations and may instead squeeze net interest margins together with the U.S. Treasury's debt issuance operations. Many market participants believe current inflation is mainly driven by supply-side factors, making it difficult for rate hikes to address effectively. LaKosh argues that this view is theoretically valid, but the key to judging whether current inflation is temporary lies in whether services inflation becomes "ignited." At present, most inflation pressure remains concentrated in goods. The problem is that if policymakers wait until inflation begins to spread into services, it may then require even more aggressive rate hikes to bring prices back under control. The post-pandemic experience has already proved this: once services inflation takes root, the policy cost rises significantly. Before the Fed acted, some argued that rates should be raised in advance to prevent inflation from becoming entrenched in services and to avoid further deterioration in rate volatility. Now the Fed has chosen to hike and has signaled a hawkish stance that further increases may be possible later this year. But this week's market reaction shows that the rate hike itself has not dispelled inflation concerns. Most economists expect it will take until at least 2028 to return to the 2% inflation target. For bank stocks, short-term earnings volatility is certainly worth watching, but the more important variable is whether the interest rate environment can stabilize as soon as possible. Moynihan expressed a similar view: "Rates will eventually stabilize, and I think that will help some of the trading activity." From an investment logic perspective, the impact of rising rates on bank earnings is not a one-way positive. During periods of strong fundamentals, credit expansion, and simultaneous net interest margin widening, bank stocks often trend higher with volatility; but if fundamental expectations come under pressure, rate hikes may instead create a "double hit" to earnings and valuations. The current market reaction shows that investors are reassessing banks' earnings prospects in an inflationary environment, and this repricing may not be over yet.