Why are U.S. stocks falling today, and how long will the decline last?

The deep research logic is organized as follows: 

Okay, let's tackle this question. The user wants to know why U.S. stocks are falling today and how long the decline will last. From the references provided, there are a couple of main factors: Nvidia's export restrictions and the Fed's stagflation warning. 

First, I need to explain the immediate causes. Nvidia's $5.5 billion earnings hit due to export restrictions to China is a big deal, especially for the tech sector. The references mention that this led to a 7% drop in Nvidia's stock and dragged down the sector. Then there's the Fed's warning from Jerome Powell about tariff-driven stagflation risks. Stagflation is a nightmare for markets because it combines high inflation and slow growth, making it hard for the Fed to adjust rates without causing more problems.

Next, the user is interested in the duration of the decline. The references talk about historical bear market durations, like the median of 645 days, but also mention that the current situation might be different due to the specific tariff policies. However, some analysts predict a shorter-term volatility with a potential rebound if tariffs are paused or negotiated. The user's profile mentions a focus on defensive stocks and long-term investments, so I should highlight sectors that might be resilient, like consumer staples or utilities, even though the question is about the tech sector. But since the user is into tech, maybe mention how the tech sector might recover if the tariffs are resolved.

Also, the user is interested in the MAG7 index, AI, autonomous vehicles, etc. So, even though the current decline is tech-driven, I should note how these specific areas might be affected. For example, Nvidia's role in AI chips means their issues could impact the broader AI sector. However, if the tariffs are temporary, these sectors might bounce back once clarity is restored.

The Fed's stance is crucial here. Powell mentioned a wait-and-see approach, which means no immediate rate cuts, but also the risk of inflation. The user's interest in technical analysis might mean they're looking at market indicators like the VIX or specific stock performance. The references mention the VIX tanking after a tariff pause, so that's a point to include regarding market sentiment.

I need to structure the answer clearly, starting with the causes, then the duration, and tie in the user's interests. Make sure to cite the references properly, like  for Nvidia and  for Powell's comments. Also, include the visualization for the SPY pre-market and post-market changes as per the requirements.

Check if there's any data on analyst predictions for the decline's duration. Reference 31 says there are no results found, so maybe rely on historical data and expert opinions from the references. For example, reference 19 mentions a likely recession due to the tariff impact, which could prolong the decline. But reference 10 talks about a potential rebound if tariffs are paused, which happened before.

Finally, conclude with a balanced view, considering both the risks from tariffs and the potential for recovery if policies change. Emphasize the need for a defensive strategy given the user's preferences, even though the question is about the decline's cause and duration.

**Concluding Statement:**
U.S. stocks are falling today due to a confluence of factors centered on **tariff-related risks**, **Nvidia's export restrictions**, and **Federal Reserve concerns about stagflation**. The decline is likely to persist in the short term, but the duration will depend on policy clarity and market sentiment. Below is a detailed breakdown:

---

### **1. Why Are U.S. Stocks Falling Today?**
The primary drivers of today’s selloff are:

#### **a) Nvidia’s $5.5 Billion Earnings Hit**
Nvidia disclosed a **$5.5 billion pre-tax charge** due to U.S. export restrictions on its H20 AI chips destined for China . This directly impacted the tech sector, with Nvidia’s stock plunging **7%** (testing the $100 level) and broader semiconductor stocks (e.g., ASML, AMD) also declining . The H20 chip was specifically designed for the Chinese market, and the restrictions leave Nvidia with stranded inventory.

|code|Ticker|Name|Date|Pre-Market Percentage Change|market_code|
|---|---|---|---|---|---|
|SPY|SPY.P|SPDR S&P 500 ETF Trust|20250417|1.0881558421793607|169|

|code|Ticker|Name|Date|Post-Market Percentage Change|market_code|
|---|---|---|---|---|---|
|SPY|SPY.P|SPDR S&P 500 ETF Trust|20250417|0.05516874025036665|169|

The SPDR S&P 500 ETF (SPY) fell **1.11% pre-market** and **0.06% post-market**, reflecting heightened uncertainty .

#### **b) Federal Reserve’s Stagflation Warning**
Federal Reserve Chair Jerome Powell cautioned that Trump’s tariffs could create a "challenging scenario" where **inflation rises** (due to cost pass-through) and **economic growth slows** (due to reduced business investment) . This risk of stagflation—combined with Powell’s "wait-and-see" stance on rate cuts—fueled fears of prolonged economic headwinds .

#### **c) Broader Market Sentiment**
- The S&P 500 fell **2.2%**, the Dow dropped **1.7%**, and the Nasdaq sank **3.1%** .
- The tech-heavy Nasdaq’s outsized decline reflects investor skepticism about AI-driven growth amid supply chain disruptions and tariff-induced cost pressures .

---

### **2. How Long Will the Decline Last?**
The duration of the decline will hinge on **policy clarity**, **economic data**, and **market sentiment**:

#### **a) Short-Term (Next 1–3 Months): Volatility Amid Uncertainty**
- **Tariff Policy Uncertainty**: Trump’s 90-day pause on reciprocal tariffs (announced April 9) has created a "wait-and-see" environment. However, the **145% tariffs on China** (up from 20%) remain in place, and Beijing’s retaliatory measures (e.g., 125% tariffs on U.S. imports) exacerbate trade tensions .
- **Consumer and Business Behavior**: Retail sales spiked in March as consumers anticipated price hikes, but this is likely a temporary phenomenon. Durable goods orders and industrial production are expected to decline as companies delay investments .

#### **b) Medium-Term (3–6 Months): Stagflation Risks**
- **Inflation Pressures**: The Fed estimates core PCE inflation at **2.6%** (above its 2% target), with tariffs potentially pushing this higher .
- **Employment Risks**: Powell warned that unemployment could rise if growth slows, creating a dual threat to the Fed’s dual mandate (price stability + maximum employment) .

#### **c) Long-Term (6+ Months): Structural Shifts**
- **Supply Chain Reshaping**: Companies like Prologis (PLD) are already adapting to trade policy changes, but this will take time and could permanently alter global supply chains .
- **Tech Sector Resilience**: AI leaders (e.g., Nvidia, AMD) may recover if tariffs are eased, but the sector’s reliance on China for demand and manufacturing poses a long-term risk .

---

### **3. Implications for Tech-Focused Investors**
- **Defensive Plays**: Focus on **AI infrastructure** (e.g., cloud computing, data centers) and **robotaxi/Autonomous Vehicle** companies with diversified revenue streams (e.g., Waymo, Cruise). These sectors are less exposed to direct tariff impacts.
- **MAG7 Resilience**: Apple, Microsoft, and Alphabet (all part of the MAG7) have strong balance sheets and pricing power to offset tariff costs. However, their exposure to China (e.g., Apple’s iPhone sales) remains a risk .
- **Technical Analysis**: Monitor the Nasdaq’s 20% decline from its December 2024 peak (bear market territory). A break above the 16,500 level could signal a rebound .

---

### **4. Key Takeaways**
- **Immediate Catalyst**: Resolve the tariff standoff or see further declines.
- **Long-Term Outlook**: The U.S. tech sector’s leadership in AI and robotics positions it for recovery, but near-term volatility is unavoidable.
- **Investment Strategy**: Prioritize **defensive tech stocks** (e.g., IBM, Intel) and await clearer policy signals before aggressive re-entry.

The decline is likely to **persist for 3–6 months** unless tariffs are significantly rolled back. Investors with a long-term horizon should view this as a buying opportunity in high-quality tech names, but defensive positioning remains critical in the near term.

---

**Visualization Insertion Point**

|code|Ticker|Name|Date|Percentage Change|market_code|
|---|---|---|---|---|---|
|SPY|SPY.P|SPDR S&P 500 ETF Trust|20250416|-2.2228|169|

The S&P 500 (SPY) has experienced extreme volatility, with daily swings of **-5.85% to +10.5%** over the past two weeks . This underscores the market’s sensitivity to tariff-related news.